Unit 1 - Force

What must a skater do to start moving forward on a skateboard?

• Pull forward on the ground

• Push backward on the ground with one foot

• Jump up and down

• Lean to the left

What is required for a push to occur, according to the text?

• Only one object

• Two objects pushing against each other

• Gravity

• Frictionless surface

What is the term for a push or pull from an interaction between two objects?

• Energy

• Friction

• Force

• Motion

How is the strength of a force measured?

• Pounds

• Joules

• Newtons

• Meters

Forces are often modeled with arrows. What does the length of the arrow represent?

• The direction of the force

• The speed of the object

• The strength of the force

• The mass of the object

Why can't an object change its motion by pushing or pulling on itself?

• Because it needs energy from outside

• Because it needs to interact with another object

• Because it is too heavy

• Because it is moving too fast

According to Newton's third law, what happens when two objects interact?

• They exert forces of different strengths on each other.

• They exert forces of the same strength in the same direction.

• They exert forces of the same strength in opposite directions.

• Only one object exerts a force on the other.

Which of the following best summarizes Newton's third law?

• For every action, there is an equal and opposite reaction.

• Objects in motion stay in motion.

• Force equals mass times acceleration.

• Energy cannot be created or destroyed.

A skateboard slides along a rail to the right, exerting a rightward force on the rail. According to Newton's third law, what force does the rail exert?

• A rightward force on the skateboard

• A leftward force on the skateboard

• No force at all

• An upward force on the skateboard

Why does a skater accelerate forward when pushing backward on the ground?

• The ground pushes forward on the skater’s foot.

• The skater’s mass increases.

• Gravity pulls the skater forward.

• The skater pushes forward on the ground.