Calculate the centripetal acceleration of the boot just before impact

Transcription

1 (ii) alculate the centripetal acceleration of the boot just before impact (iii) iscuss briefly the radial force on the knee joint before impact and during the impact (4) (Total 7 marks) Polesworth High School 11

2 130. The graph shows how the momentum of two colliding railway trucks varies with time. Truck has a mass of kg and truck has a mass of kg. The trucks are travelling in the same direction. momentum/10 3 kg m s time/s (a) alculate the change in momentum of (i) truck, (ii) truck. (4) (b) omplete the following table. Initial velocity/m s 1 Final velocity/m s 1 Initial kinetic energy/j Final kinetic energy/j truck truck (4) Polesworth High School 1

3 (c) State and explain whether the collision of the two trucks is an example of an elastic collision (3) (Total 11 marks) 131. spring is suspended from a fixed point. mass attached to the spring is set into vertical undamped simple harmonic motion. When the mass is at its lowest position, which one of the following has its minimum value? the potential energy of the system the kinetic energy of the mass the acceleration of the mass the tension in the spring (Total marks) 13. The time period of a simple pendulum is doubled when the length of the pendulum is increased by 3.0 m. What is the original length of the pendulum? 1.0 m 1.5 m 3.0 m 6.0 m (Total marks) Polesworth High School 13

4 133. The Earth has density ρ and radius R. The gravitational field strength at the surface is g. What is the gravitational field strength at the surface of a planet of density ρ and radius R? g g 4 g 16 g (Total marks) 134. particle of mass m moves in a circle of radius r at uniform speed, taking time T for each revolution. What is the kinetic energy of the particle? π T π m r m r T π m r T π T m r (Total marks) Polesworth High School 14

5 135. Two protons, each of mass m and charge e, are a distance d apart. Which one of the following electrostatic force expressions correctly gives the ratio for the forces acting between them? gravitational force 4πε 0 e Gm Ge 0 4πε m e m 4πε G 0 e 0 4πε Gm (Total marks) Polesworth High School 15

6 136. The graph shows how the gravitational potential, V, varies with the distance, r, from the centre of the Earth. 0 0 surface r V What does the gradient of the graph at any point represent? the magnitude of the gravitational field strength at that point the magnitude of the gravitational constant the mass of the Earth the potential energy at the point where the gradient is measured (Total marks) Polesworth High School 16

7 µ 16µ 10 mm The diagram shows two charges, +4 µ and 16 µ, 10 mm apart. What is the distance from the +4 µ charge to the point between the two charges, where the resultant electric potential is zero? 4 mm 40 mm 80 mm 96 mm (Total marks) 138. n electron travelling at constant speed enters a uniform electric field at right angles to the field. While the electron is in the field it accelerates in a direction which is in the same direction as the electric field. in the opposite direction to the electric field. in the same direction as the motion of the electron. in the opposite direction to the motion of the electron. (Total marks) Polesworth High School 17

8 139. loudspeaker l air water glass tube tap small loudspeaker emitting sound of constant frequency is positioned a short distance above a long glass tube containing water. When water is allowed to run slowly out of the tube, the intensity of the sound heard increases whenever the length l (shown above) takes certain values. (a) Explain these observations by reference to the physical principles involved. You may be awarded marks for the quality of written communication in your answer (4) Polesworth High School 18

9 (b) With the loudspeaker emitting sound of frequency 480 Hz, the effect described in part (a) is noticed first when l = 168 mm. It next occurs when l = 53 mm. Use both values of l to calculate (i) the wavelength of the sound waves in the air column, (ii) the speed of these sound waves. (4) (Total 8 marks) 140. (a) s a capacitor was charged from a 1 V supply, a student used a coulomb meter and a voltmeter to record the charge stored by the capacitor at a series of values of potential difference across the capacitor. The student then plotted a graph of pd (on the y-axis) against charge (on the x-axis). (i) Sketch the graph obtained. pd 0 0 charge (ii) State what is represented by the gradient of the line. Polesworth High School 19

10 (iii) State what is represented by the area enclosed by the line and the x-axis of the graph. (3) (b) The student then connected the capacitor as shown in the diagram below to carry out an investigation into the discharge of the capacitor. S 1 S 1 V to voltage sensor 6800µ F 5.6 kω 5.6 kω The student used a voltage sensor, datalogger and computer to obtain values for the pd across the capacitor at various times during the discharge. (i) t time t = 0, with switch S open, switch S 1 was moved from position to position. alculate the pd across the capacitor when t = 6 s. (ii) t time t = 6 s, as the discharge continued, the student closed switch S. alculate the pd across the capacitor 40 s after switch S 1 was moved from position to position. Polesworth High School 130

11 (iii) Sketch a graph of pd against time for the student s experiment described in parts (b)(i) and (b)(ii). pd/v time/s (7) (Total 10 marks) 141. (a) State, in words, Newton s law of gravitation (3) (b) y considering the centripetal force which acts on a planet in a circular orbit, show that T R 3, where T is the time taken for one orbit around the Sun and R is the radius of the orbit (3) Polesworth High School 131

12 (c) The Earth s orbit is of mean radius m and the Earth s year is 365 days long. (i) The mean radius of the orbit of Mercury is m. alculate the length of Mercury s year. (ii) Neptune orbits the Sun once every 165 Earth years. alculate the ratio distance from Sun to Neptune. distance from Sun to Earth (4) (Total 10 marks) Polesworth High School 13

13 14. ball bearing rolls on a concave surface, as shown in the diagram, in approximate simple harmonic motion. It is released from and passes through the lowest point before reaching. It then returns through the lowest point. t which stage,,, or, does the ball bearing experience maximum acceleration to the left? (Total marks) b 143. body moves with simple harmonic motion of amplitude and frequency. π What is the magnitude of the acceleration when the body is at maximum displacement? zero 4π b b 4π b (Total marks) µf capacitor is charged so that the voltage across its plates rises at a constant rate from 0 V to 4.0 V in 0 s. What current is being used to charge the capacitor? 5 µ 0 µ 40 µ 80 µ (Total marks) Polesworth High School 133

14 145. What is the value of the angular velocity of a point on the surface of the Earth? rad s rad s rad s rad s 1 (Total marks) 146. The diagram shows two positions, X and Y, at different heights on the surface of the Earth. X Which line, to, in the table gives correct comparisons at X and Y for gravitational potential and angular velocity? gravitational potential at X compared with Y Y angular velocity at X compared with Y greater greater greater same greater smaller same same (Total marks) Polesworth High School 134

15 147. projectile moves in a gravitational field. Which one of the following is a correct statement for the gravitational force acting on the projectile? The force is in the direction of the field. The force is in the opposite direction to that of the field. The force is at right angles to the field. The force is at an angle between 0 and 90 to the field. (Total marks) 148. Two parallel metal plates separated by a distance d have a potential difference V across them. What is the magnitude of the electrostatic force acting on a charge Q placed midway between the plates? d Q d VQ d VQ d VQ d Qd V (Total marks) Polesworth High School 135

16 149. P axle Q I I uniform magnetic field S R coil, mounted on an axle, has its plane parallel to the flux lines of a uniform magnetic field, as shown. When a current I is switched on, and before the coil is allowed to move, there are no forces due to on the sides PQ and RS. there are no forces due to on the sides SP and QR. sides SP and QR attract each other. sides PQ and RS attract each other. (Total marks) 150. Protons, each of mass m and charge e, follow a circular path when travelling perpendicular to a magnetic field of uniform flux density. What is the time taken for one complete orbit? πe m m πe e πm πm e (Total marks) Polesworth High School 136

17 151. (a) spring, which hangs from a fixed support, extends by 40 mm when a mass of 0.5 kg is suspended from it. (i) alculate the spring constant of the spring. (ii) n additional mass of 0.44 kg is then placed on the spring and the system is set into vertical oscillation. Show that the oscillation frequency is 1.5 Hz. (4) (b) With both masses still in place, the spring is now suspended from a horizontal support rod that can be made to oscillate vertically, as shown in the figure below, with amplitude 30 mm at several different frequencies. support rod vertical oscillations spring masses Polesworth High School 137

18 escribe fully, with reference to amplitude, frequency and phase, the motion of the masses suspended from the spring in each of the following cases. (i) The support rod oscillates at a frequency of 0. Hz. (ii) The support rod oscillates at a frequency of 1.5 Hz. (iii) The support rod oscillates at a frequency of 10 Hz. (6) (Total 10 marks) Polesworth High School 138

19 µf capacitor is charged fully from a 1 V battery. t time t = 0 the capacitor begins to discharge through a resistor. When t = 5 s the energy remaining in the capacitor is one quarter of the energy it stored at 1 V. (a) etermine the pd across the capacitor when t = 5s () (b) (i) Show that the time constant of the discharge circuit is 36 s. (ii) alculate the resistance of the resistor. (4) (Total 6 marks) Polesworth High School 139

20 153. (a) rtificial satellites are used to monitor weather conditions on Earth, for surveillance and for communications. Such satellites may be placed in a geo-synchronous orbit or in a low polar orbit. escribe the properties of the geo-synchronous orbit and the advantages it offers when a satellite is used for communications. You may be awarded marks for the quality of written communication in your answer (3) (b) satellite of mass m travels at angular speed ω in a circular orbit at a height h above the surface of a planet of mass M and radius R. (i) Using these symbols, give an equation that relates the gravitational force on the satellite to the centripetal force. (ii) Use your equation from part (b)(i) to show that the orbital period, T, of the satellite is given by T ( R h) 4 + = GM π 3 Polesworth High School 140

21 (iii) Explain why the period of a satellite in orbit around the Earth cannot be less than 85 minutes. Your answer should include a calculation to justify this value. mass of the Earth = kg kg radius of the Earth = m (6) (c) escribe and explain what happens to the speed of a satellite when it moves to an orbit that is closer to the Earth () (Total 11 marks) Polesworth High School 141

22 154. (a) n electron travels at a speed of ms 1 in a horizontal path through a vacuum. The electron enters the uniform electric field between two parallel plates, 30 mm long and 15 mm apart, as shown in the figure below. potential difference of 1400 V is maintained across the plates, with the top plate having positive polarity. ssume that there is no electric field outside the shaded area. + electron 15 mm 30 mm (i) Show that the electric field strength between the plates is Vm 1. (ii) alculate the time taken by the electron to pass through the electric field. (iii) Show that the acceleration of the electron whilst in the field is m s and state the direction of this acceleration. (5) Polesworth High School 14

23 (b) etermine the magnitude and direction of the velocity of the electron at the point where it leaves the field (3) (Total 8 marks) 155. (a) State two quantities that are conserved in an elastic collision. quantity 1:... quantity :... () (b) gas molecule makes an elastic collision with the walls of a gas cylinder. The molecule is travelling at 450 m s 1 at right angles towards the wall before the collision. (i) What is the magnitude and direction of its velocity after the collision? Polesworth High School 143

24 (ii) alculate the change in momentum of the molecule during the collision if it has a mass of kg. (4) (c) Use Newton s laws of motion to explain how the molecules of a gas exert a force on the wall of a container. You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer (4) (Total 10 marks) 156. mass M on a spring oscillates along a vertical line with the same period T as an object O in uniform circular motion in a vertical plane. When M is at its highest point, O is at its lowest point. M O Polesworth High School 144

25 What is the least time interval between successive instants when the acceleration of M is exactly in the opposite direction to the acceleration of O? T 4 T 3T 4 T (Total marks) 157. particle of mass m oscillates with amplitude at frequency f. What is the maximum kinetic energy of the particle? 1 π mf π mf π mf 4 π mf (Total marks) µf capacitor, initially uncharged, is charged by a steady current of 50 µ. How long will it take for the potential difference across the capacitor to reach.5 V? 0 s 50 s 100 s 400 s (Total marks) Polesworth High School 145

26 159. In experiments to pass a very high current through a gas, a bank of capacitors of total capacitance 50 µf is charged to 30 kv. If the bank of capacitors could be discharged completely in 5.0 m s what would be the mean power delivered? kw 110 kw 4.5 MW 9.0 MW (Total marks) 160. For a particle moving in a circle with uniform speed, which one of the following statements is correct? The displacement of the particle is in the direction of the force. The force on the particle is in the same direction as the direction of motion of the particle. The momentum of the particle is constant. The kinetic energy of the particle is constant. (Total marks) Polesworth High School 146

27 161. Which one of the following graphs correctly shows the relationship between the gravitational force, F, between two masses and their separation r. 1 1 (Total marks) 16. When at the surface of the Earth, a satellite has weight W and gravitational potential energy U. It is projected into a circular orbit whose radius is equal to twice the radius of the Earth. Which line, to, in the table shows correctly what happens to the weight of the satellite and to its gravitational potential energy? weight becomes becomes W W 4 gravitational potential energy increases by increases by U U remains W increases by U becomes W 4 increases by U (Total marks) Polesworth High School 147

28 163. Two protons are m apart. pproximately how many times is the electrostatic force between them greater than the gravitational force between them? (Total marks) 164. Particles of mass m carrying a charge Q travel in a circular path of radius r in a magnetic field of flux density with a speed v. How many of the following quantities, if changed one at a time, would change the radius of the path? m Q v one two three four (Total marks) 165. (a) Give an equation for the frequency, f, of the oscillations of a simple pendulum in terms of its length, l, and the acceleration due to gravity, g State the condition under which this equation applies () Polesworth High School 148

29 (b) The bob of a simple pendulum, of mass kg, swings with an amplitude of 51 mm. It takes 46.5 s to complete 5 oscillations. alculate (i) the length of the pendulum, (ii) the magnitude of the restoring force that acts on the bob when at its maximum displacement. (6) (Total 8 marks) 166. Progressive waves are generated on a rope by vibrating vertically the end, P, in simple harmonic motion of amplitude 90 mm, as shown in the figure below. The wavelength of the waves is 1. m and they travel along the rope at a speed of 3.6 m s 1. ssume that the wave motion is not damped. 0.4 m wave speed 3.6 m s 1 P Q vertical vibrations Polesworth High School 149

30 (a) Point Q is 0.4 m along the rope from P. escribe the motion of Q in as much detail as you can and state how it differs from the motion of P. Where possible, give quantitative values in your answer. You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer (5) (b) alculate the maximum speed of point P (3) (Total 8 marks) 167. (a) (i) efine the electric field strength, E, at a point in an electric field. Polesworth High School 150

31 (ii) State whether E is a scalar or a vector quantity. (3) (b) Point charges of +4.0 n and 8.0 n are placed 80 mm apart, as shown in the figure below. 80 mm +4.0 n 8.0 n P (i) alculate the magnitude of the force exerted on the +4.0 n charge by the 8.0 n charge. (ii) etermine the distance from the +4.0 n charge to the point, along the straight line between the charges, where the electric potential is zero. (4) Polesworth High School 151

32 (c) Point P in the figure above is equidistant from the two charges. (i) raw two arrows on the figure above at P to represent the directions and relative magnitudes of the components of the electric field at P due to each of the charges. (ii) Hence draw an arrow, labelled R, on the figure above at P to represent the direction of the resultant electric field at P. (3) (Total 10 marks) 168. (a) In an experiment to illustrate electromagnetic induction, a permanent magnet is moved towards a coil, as shown in Figure 1, causing an emf to be induced across the coil. Figure 1 coil N permanent magnet S to voltage sensor Using Faraday s law, explain why a larger emf would be induced in this experiment if a stronger magnet were moved at the same speed. You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer (3) Polesworth High School 15

33 (b) conductor of length l is moved at a constant speed v so that it passes perpendicularly through a uniform magnetic field of flux density, as shown in Figure. l v Figure uniform magnetic field (perpendicular to the plane of the diagram) over this region (i) Give an expression for the area of the magnetic field swept out by the conductor in time t. (ii) Show that the induced emf,, across the ends of the conductor is given by = lv. (3) Polesworth High School 153

34 (c) simple electrical generator can be made from a copper disc, which is rotated at right angles to a uniform magnetic field, directed into the plane of the diagram (Figure 3). n emf is developed across terminals P (connected to the axle) and Q (connected to a contact on the edge of the disc). Figure 3 uniform magnetic field (acting into the plane of the diagram) over this region copper disc axel M contact P Q The radius of the disc is 64 mm and it is rotated at 16 revolutions per second in a uniform magnetic field of flux density 8 mt. (i) alculate the angular speed of the disc. (ii) alculate the linear speed of the mid-point M of a radius of the disc. Polesworth High School 154

35 (iii) Hence, or otherwise, calculate the emf induced across terminals P and Q. (5) (Total 11 marks) 169. For the two physical quantities, impulse and force, which one of the following is correct? Impulse is a scalar and force is a scalar. Impulse is a scalar and force is a vector. Impulse is a vector and force is a scalar. impulse is a vector and force is a vector. (Total 1 mark) 170. particle of mass m strikes a rigid wall perpendicularly from the left with velocity v. If the collision is perfectly elastic, the change in momentum of the particle which occurs as a result of the collision is mv to the right. mv to the left. mv to the left. zero. (Total 1 mark) Polesworth High School 155

36 171. force, F, varies with time, t, as shown by the graph and is applied to a body initially at rest on a smooth surface. What is the momentum of the body after 5.0 s? zero. 1.5 N s. 5 N s. 50 N s. (Total 1 mark) 17. The rate of change of momentum of a body falling freely under gravity is equal to its weight. power. kinetic energy. potential energy. (Total 1 mark) Polesworth High School 156

37 173. What is the value of the angular velocity of a point on the surface of the Earth? rad s rad s rad s rad s 1 (Total 1 mark) 174. model car moves in a circular path of radius 0.8 m at an angular speed of π rad s 1. What is its displacement from point P, 6 s after passing P? zero 1.6 m 0.4 πm 1.6 πm (Total 1 mark) Polesworth High School 157

38 175. particle of mass m moves horizontally at constant speed v along the arc of a circle from P 1 to P under the action of a force. What is the work done on the particle by the force during this displacement? zero πmv mv mv (Total 1 mark) 176. body moves with simple harmonic motion of amplitude 0.50 m and period 4π seconds. What is the speed of the body when the displacement of the body from the equilibrium position is 0.30 m? 0.10 m s m s m s m s 1 (Total 1 mark) Polesworth High School 158

39 177. The time period of a simple pendulum is doubled when the length of the pendulum is increased by 3.0 m. What is the original length of the pendulum? 1.0 m 1.5 m 3.0 m 6.0 m (Total 1 mark) 178. Which one of the following statements is not true for a body vibrating in simple harmonic motion when damping is present? The damping force is always in the opposite direction to the velocity. The damping force is always in the opposite direction to the displacement. The presence of damping gradually reduces the maximum potential energy of the system. The presence of damping gradually reduces the maximum kinetic energy of the system. (Total 1 mark) 179. The Earth has density ρ and radius R. The gravitational field strength at the surface is g. What is the gravitational field strength at the surface of a planet of density ρ and radius R? g g 4g 16g (Total 1 mark) Polesworth High School 159

40 180. Which one of the following graphs correctly shows the relationship between the gravitational force, F, between two masses and their separation, r? (Total 1 mark) 181. Near the surface of a planet the gravitational field strength is uniform and for two points, 10 m apart vertically, the gravitational potential difference is 3 J kg 1. How much work must be done in raising a mass of 4 kg vertically through 5 m? 3 J 6 J 1 J 15 J (Total 1 mark) Polesworth High School 160