HP Unit 02 - Forces and Newton's Laws

HP Unit 02 - Forces and Newton's Laws

Weight and Friction

• The weight of an object is the force pulling the object downward. On Earth, this is the gravitational force of the Earth.

• Friction is the force that resists motion.  Friction exists between two touching surfaces because even the smoothest looking surface is quite rough on a microscopic scale.

Multiple Choice

A measure of how much matter an object has is--

• weight

• gravity

• mass

• volume

Multiple Choice

Weight is _________.

• the quantity of matter in an object.

• the measure of an object's inertia.

• the force exerted by gravity on an object's mass.

• equal to the mass of an object.

Multiple Choice

The rougher the surface, the faster an object will travel over the surface.

• True
• False

Multiple Choice

The amount of friction depends on the force of the objects pressing together.

• True

• False

Multiple Choice

Which type of friction occurs when objects are not moving?

• static

• sliding

• fluid

• rolling

Introducing Newton's Three Laws

• 1st Law: An object at rest will stay at rest and an object in motion will remain in motion.

• 2nd Law: The acceleration of an object is directly proportional to the net force on the object and inversely proportional to the mass of the object.

• 3rd Law: whenever one object exerts a force on a second object, the second object also exerts a force on the first object, equal in magnitude and opposite in direction.

Multiple Choice

Inertia is a force that keeps stationary objects at rest and moving objects in motion at a constant velocity.

• True

• False

Multiple Choice

An object in motion will stay in what kind of motion as long as the net forces acting on it are zero?

• slowing motion in a straight line

• accelerating motion in a straight line

• constant motion in a straight line

• constant motion in an unpredictable direction

Multiple Choice

An object's velocity can be changed by changing its speed, its direction, or both.

• True

• False

Multiple Choice

What happens when unbalanced forces act on an object at rest?

• the object remains at rest

• the object begins moving in an unpredictable direction

• the object begins moving in the direction of the net force

• the object begins moving opposite to the direction of net force

Multiple Choice

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction force is...

• The grip of the player's hands on the ball
• the air resistance of the ball
• the force of the ball against the bat

Multiple Choice

When a heavy football player and a light one run into each other, who exerts more force?

• The light one

• They exert the same force on each other

• The heavy one