Q: Who established the law of universal gravitation? A: Newton. Q: What is a spring scale used for? A: To measure weight

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1 Q: Who established the law of universal gravitation? A: Newton Q: What is a spring scale used for? A: To measure weight Q: What is the Law of Universal Gravitation? A: Everything in the universe has gravity. Q: What is mass? A: Mass is the amount of matter in an object Q: What is weight? A: Weight is a measurement of the force of gravity on an object. Q: Why do astronauts on the moon seem to bounce around so effortlessly? A: The moon has 1/6 th the amount of gravity that the Earth has. Q: What two factors determine the amount of gravitational attraction between two objects? A: The mass of an object and the distance between two objects. Q: What will happen on Earth if you drop a hammer and a feather at the same time and from the same height? Why? A: The hammer will land first because air resistance has a larger affect on the feather causing it to slow down as it falls. Q: What will happen on the Moon if you drop a hammer and a feather at the same time and from the same height? Why? A: They will land at the same time. The moon doesn t have an atmosphere so neither object is affected by air resistance. Q: Would your weight be the same at the base of a mountain and at the top of the same mountain? Explain. A: At the top of the mountain you would weigh a little bit less than at the base of the same mountain. This is because at the top of the mountain you are farther away from the center of the Earth.

2 Q: How can we tell if an object is moving? A: Motion is always observable as a change in an object s position compared to objects that are still, or not moving. Q: How do you calculate speed? A: Distance divided by time Q: What is velocity? A: Velocity is the speed of an object in a particular direction. Q: True or False? Two objects traveling at the same velocity stay in the same position relative to each other. A: True Q: What happens to the velocity of an object moving in a circle, like a planet orbiting around a star? A: The velocity of an object moving in a circle is constantly changing, because the direction of the movement is constantly changing. Q: What changes an objects velocity? A: A force. Q: What are two factors that affect momentum? A: how much mass an object has and its velocity (how fast it is going and in what direction) Q: How is it possible for two objects traveling the same speed to have different velocities? A: they are traveling in different directions Q: How is it possible for two objects traveling in the same direction to have different velocities? A: the have different speeds Q: What is Newton s 1 st Law of Motion? A: An object at rest will remain at rest, and an object in motion will remain in motion in a straight line unless a force acts on the object.

3 Q: Objects tend to keep on doing what they are currently doing unless what acts on them to change this condition? A: A force Q: What do you call the resistance of an object to a change in motion? A: inertia. Remember even objects at rest have inertia. Q: What is the other name for Newton s 1 st Law of Motion? A: The Law of Inertia Q: What two forces often act on objects causing them to slow down and stop? A: gravity and friction Q: A substance that decreases friction is called a. A: lubricant (example: oil) Q: What property of objects makes them tend to resist a change in motion? A: Inertia Q: What is an unbalanced force? A: An unbalanced force is a force without an equal force in the opposite direction. Q: What changes when an unbalance force acts on an object? A: when an unbalanced force acts on an object, it changes the velocity of the object (its speed, its direction, or both). Q: What is acceleration? A: Acceleration is the rate of change in velocity of an object. Q: What two properties affect acceleration of an object? A: the size of the force and the mass of the object

4 Q: Fill in the blank. The greater the force, the is the acceleration, or change in velocity. A: The greater the force, the greater is the acceleration, or change in velocity. Q: Fill in the blank. The greater the mass, the is the acceleration, or change in velocity. A: The greater the mass, the smaller is the acceleration, or change in velocity. Q: Do heavier objects require more or less force to move the same distance as lighter objects? A: They require more force. Q: If I push an object north, what direction will it go? A: North Q: If I push two objects with the same amount of force and in the same direction which will move the fastest? A: The lighter object will move the fastest. Q: why are heavier objects harder to stop and start than lighter objects? A: Because they have more mass. Q: What is the equation for force that we use when we discuss Newton s 2 nd Law of Motion? A: Force = mass x acceleration Q: What unit do we use for force? A: N (Newton) Q: What is Newton s 3 rd Law of Motion? A: For every action force there is an equal and opposite reaction force. Q: True or False? Forces never come in pairs. A: False! Forces always come in pairs!

5 Q: What is true about action and reaction forces? A: Action and reaction forces are always equal in size and opposite in direction. Q: Why does an object accelerate as it falls? A: The acceleration of a falling object is due to the force of gravity. Q: What happens when forces are balanced? A: Nothing moves Q: What happens to the balance between gravitational potential energy and mechanical kinetic energy as you start a pendulum moving? Q: The pendulum will have the most gravitational potential energy and the least mechanical kinetic energy just before it is released. It will have the most mechanical kinetic energy and the least amount of gravitational potential energy at the bottom on its swing. This is a gradual change between these two forms of energy. Q: What is the measure of the total distance an object has moved divided by the total elapsed time called? A: Average speed Q: Why is the velocity of an object moving in a circle constantly changing? A: Velocity is speed in any given direction. The velocity of an object moving in a circle is constantly changing because the direction of movement is constantly changing. Q: If you slide an object to the east, in what direction does the force of friction act to resist the motion? A: the force of friction is to the west (opposite the original force). Q: What is a hypothesis? A: It is an educated prediction scientists make before doing an experiment.