C B A T 3 T 2 T What is the magnitude of the force T 1? A) 37.5 N B) 75.0 N C) 113 N D) 157 N E) 192 N

Transcription

1 Three boxes are connected by massless strings and are resting on a frictionless table. Each box has a mass of 15 kg, and the tension T 1 in the right string is accelerating the boxes to the right at a rate of 2.5 m/s 2. T 3 T 2 C B A T 1 1. What is the magnitude of the force T 1? A) 37.5 N B) 75.0 N C) 113 N D) 157 N E) 192 N 2. If the boxes start from rest at t=0. How far do they travel during the 3 seconds between time t = 1 seconds and t = 4 seconds? A) 11.3 m B) 18.8 m C) 20.0 m

2 Three boxes are connected by massless strings and are resting on a frictionless table. Each box has a mass of 15 kg, and the tension T 1 in the right string is accelerating the boxes to the right at a rate of 2.5 m/s 2. T 3 T 2 C B A T 1 3. What is the net horizontal force on box A? A) 37.5 N B) 75.0 N C) 113 N 4. What is the force on box B due to T 3? A) 75.0 N to the left B) 37.5 N to the left C) 37.5 N to the right D) 75.0 N to the right E) 113 N to the right

3 The next two questions refer to the following situation. A block of mass M is attached to the ceiling of an elevator by two strings. 5. Which one of the following equations applies to this system when the elevator is at rest? A) T 1 cos 1 T 2 cos 2 0 B) T 1 sin 1 T 2 sin 2 0 C) T 1 cos 1 T 2 cos 2 Mg D) T 1 sin 1 T 2 sin 2 Mg E) T 1 T 2 6. Let T 1 be the tension in wire one when the elevator is moving upwards with a speed 8 m/s, but slowing down as it comes to a stop at the top floor. How does this tension, compare to T 1, the tension in the wire when the elevator is at rest. A) T 1 '= T 1 B) T 1 '< T 1 C) T 1 ' > T 1

4 A 200 kg crate sits on the bed of a truck. The truck is accelerating to the right at 1.0 m/sec 2. The static coefficient of friction between the crate and the truck bed is s = The kinetic coefficient is k = The crate does not slide relative to the truck bed. 7. The direction of the friction force on the crate from the truck is A) to the left B) to the right 8. The magnitude of the friction force on the crate is A) 490 N B) 294 N C) 200 N D) 50 N E) 30 N

5 A 200 kg crate sits on the bed of a truck. The truck is accelerating to the right at 1.0 m/sec 2. The static coefficient of friction between the crate and the truck bed is s = The kinetic coefficient is k = The crate does not slide relative to the truck bed. 9. Now the truck accelerates at 8m/sec 2 (powerful truck!) and the crate slides back on the truck bed. What is the acceleration of the crate relative to the ground? A) 8m/sec 2 to the right B) 1.5 m/sec 2 to the right C) zero D) 1.5 m/sec 2 to the left E) 8m/sec 2 to the left

6 A Ferris wheel has a radius of 8 meters, and spins counterclockwise with a constant angular velocity = 0.8 radians/second. (Cart B is going up at the instant shown). 10. What is the speed of the cart A at the instant shown? A) 0 B) 6.4 m/s C) 8.0 m/s 11. What is the x component of the acceleration of cart B at the instant shown? A) -9.8 m/s 2 B) -5.1 m/s 2 C) 0 D) 5.1 m/s 2 E) +9.8 m/s 2

7 A Ferris wheel has a radius of 8 meters, and spins counterclockwise with a constant angular velocity = 0.8 radians/second. (Cart B is going up at the instant shown). 12. What is the y component of the acceleration of cart B at the instant shown? A) -9.8 m/s 2 B) -5.1 m/s 2 C) 0 D) 5.1 m/s 2 E) +9.8 m/s What is the maximum force the Ferris wheel will exert on 75kg person as they go around the ride? A) 380 N B) 740 N C) 1,120 N

8 Scientists want to place a 2800 kg satellite in a circular orbit around Mars. They plan to have the satellite orbit at a speed of 2100 m/s m mars = 6.5 x kg r mars = 3.40 x 10 6 m G = 6.67 x N-m 2 /kg How far above the surface of mars will the satellite orbit? A) 3.4 x 10 6 m B) 5.1 x 10 6 m C) 6.4 x 10 6 m D) 7.3 x 10 6 m E) 8.5 x 10 6 m 15. Compare T 1 the time needed to complete one orbit with the above parameters (v=2100 m/s) to T 2 the time needed to complete an orbit if instead it was placed in a circular orbit about mars with v=4200 m/s. A) T 2 < (1/2) T 1 B) T 2 = (1/2) T 1 C) T 2 > (1/2) T 1

9 A box is attached to a spring with a spring constant of 350 N/m on a frictionless incline that makes an angle of 30 degrees with respect to horizontal as shown. The box is at rest when the spring is stretched 0.15 meters from its equilibrium length. m What is the mass of the box? 30 A) 5.4 kg B) 6.2 kg C) 10.7 kg 17. The mass is released from the spring and slides down the incline. What is the speed of the block after it has moved a distance of 0.4 meters along the incline? A) 1.4 m/s B) 2.0 m/s C) 2.8 m/s

10 An airplane travels with a velocity of 150 m/s due east with respect to the air. The air is moving with a speed of 50 m/s with respect to the ground at an angle of 45 degrees North of East. 18. What is the speed of the plane with respect to the ground? A) 154 m/s B) 185 m/s C) 188 m/s 19. What is the heading of the plane with respect to the ground? (0 degrees is due East, 90 degrees is due North). A) 11 degrees North of East B) 16 degrees North of East C) 19 degrees North of East

11 A cannon ball is fired at a wall located 450 meters away (the diagram is not to scale). The initial horizontal component of the balls velocity is 90 m/s and its initial angle is 24 degrees. v i y 20. What is the initial speed of the ball? A) 75 m/s B) 99 m/s C) 114 m/s 450 m x 21. How long does it take for the ball to reach the wall? A) 5.0 s B) 5.5 s C) 8.2 s

12 A cannon ball is fired at a wall located 450 meters away (the diagram is not to scale). The initial horizontal component of the balls velocity is 90 m/s and its initial angle is 24 degrees. v i y 22. What is the maximum height the ball reaches? A) 82 m B) 164 m C) 246 m 450 m x 23. How high above the ground is the ball when it reaches the wall? A) 34 m B) 78 m C) 128 m

13 The graph below shows data obtained with the Physics 211 cart, track and motion detector. The position of a cart is shown as a function of time. The time interval between measurements is 0.05 s. 24. Which of the following statements about the velocity of the cart is correct? A) The velocity of the cart is positive from 0 s to 5 s. B) The velocity of the cart is positive from 1 s to 4 s. C) The velocity of the cart is positive only at 2.5 s. D) The velocity of the cart is positive from 1 s to 2 s. E) The velocity of the cart is positive from 3 s to 4 s.

14 The graph below shows data obtained with the Physics 211 cart, track and motion detector. The position of a cart is shown as a function of time. The time interval between measurements is 0.05 s. 25. Which of the following statements about the acceleration of the cart is correct? A) From 1 s to 4 s the acceleration of the cart goes from positive to negative. B) From 1 s to 4 s the acceleration of the cart goes from negative to positive. C) The acceleration of the cart does not change sign between 1 s and 4 s.

15 The graph below shows data obtained with the Physics 211 cart, track and motion detector. The position of a cart is shown as a function of time. The time interval between measurements is 0.05 s. 26. What is the average velocity of the cart between 1.5 s and 2.5 s? A) 1.0 m / s B) 0.8 m / s C) 0.2 m /s D) 0.6 m / s E) 0.8 m / s