Any external force that acts against movement is called __________.
Human muscles have an efficiency of about __________.
Describe what would happen if, while wearing rollerskates, you pushed as hard as you could against a wall. Why does this happen?
You would roll backward, away from the wall. When you push on the wall, the wall pushes back on you with an equal force in the opposite direction. Because you are wearing rollerskates, there is little friction to prevent you from moving.
Grady has been playing soccer for years. He is considered an expert in many aspects of the game, including kicking, passing, and dribbling. How could Grady have achieved the status of expert?
Which object would have the most momentum?
Describe what would happen if, while wearing rollerskates, you pushed as hard as you could against a wall. Why does this happen?
If, while wearing rollerskates, a person pushed against a wall as hard as he or she could, the force of the push would be opposed by the force of the wall pushing back against the pusher. Because the wall is solid and grounded, and the pusher is wearing roller skates, the pusher would end up rolling in the direction opposite to the force of the push.
Earth's gravity acts upon objects with a steady force of __________.
Describe the four main types of resistance forces.
The four main resistance forces are objects with mass, inertia, and momentum; friction; gravity; and air resistance. Objects with mass are able to provide resistance by colliding with other objects. Friction slows objects down by providing a steady resistance when the objects are in contact with and rubbing against a surface. Gravity provides a steady downward pull towards the center of Earth's mass. Air resistance is the cumulative force provided by millions of oxygen atoms being displaced.
When an object has its motion changed, the cause is generally __________.
Describe the four main types of resistance forces.
The measure of an object's mass and velocity is called __________.
Human muscles have an efficiency of about __________.
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