Cast Physics

The law of universal gravitation states that any two objects in the uni-verse that have mass, without exception,

• attract each other.

• repel each other.

• combine to provide a balanced force.

• create friction

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According to the law of conservation of momentum, when two objects collide in the absence of outside forces,

• velocity decreases

• velocity increases

• the objects have the same momentum before and after they collide.

• the objects have more momentum after they collide than they did before.

According to Newton’s third law of motion, when a hammer strikes and exerts force on a nail, the nail

• creates a friction with the hammer.

• disappears into the wood.

• exerts an equal and opposite force on the hammer.

• moves at a constant speed.

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The force of gravity between you and Earth is greater than the force of gravity between you and a car because Earth has more ____________________ than the car.

• mass

• density

• force

• friciton

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According to Newton’s third law of motion, the strength of a reaction force is ____________________ the strength of the action force.

• equal to

• negative to

• positive to

• greater than

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A skydiver with a mass of 70 kg accelerates to Earth at a rate of 9.8 m/s2 due to gravity. What is the force on the skydiver?

• 79.8 Newtons

• 7.14 Newtons

• 0.14 Newtons

• 68.60 Newtons

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Define the term inertia.

• the amount of matter in an object

• the amount of space an object takes up

• the tendency of an object to resist a change in motion, determined by mass

• The force that one surface exerts on another when the two rub against each other

What happens when two forces act in the same direction?

• They cancel each other out.

• The stronger one prevails.

• Their strengths are added.

• Their sum divided by two is the total force.

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The greater the mass of an object,

• the easier the object starts moving.

• the greater its inertia.

• the more balanced it is.

• the more space it takes up.

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The force of gravity on a person or object on the surface of a planet is called

• mass.

• weight.

• terminal velocity

• free fall.

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