Kinetic Energy
What two factors determine an object’s kinetic energy?
mass & speed
What type of potential energy depends on height?
Gravitational
When a moving object slows down, some kinetic energy is converted into ___ and ___.
Heat and sound
What force opposes motion between two surfaces?
Friction
Newton’s 3rd Law: For every action, there is an equal and opposite ___.
Reaction
If a car doubles its speed, what happens to its kinetic energy?
quadruples
Increasing which variable will always increase gravitational potential energy?
Height
The law of conservation of energy states that energy cannot be ___ or ___.
Created or destroyed
An unbalanced force causes an object to ___.
accelerate
When you push on a wall, the wall pushes back with an ___ force.
Equal
Between a 2-kg object at 4 m/s and a 4-kg object at 2 m/s, which has more KE?
same KE
Two identical books are placed on shelves at different heights. Which has more PE and why?
Higher one due to height
When a ball falls, PE is converted into ___.
Kinetic
If two equal forces act in opposite directions, the net force is ___.
Zero
A rocket moves upward because gases are pushed ___.
downward
A student says “A heavier object always has more kinetic energy.” Explain why this is not always true.
Doubling an object’s mass will ___ its gravitational potential energy.
Double
A toaster converts electrical energy into ___ energy
Thermal (heat)
A greater unbalanced force on an object results in a ___ acceleration.
increased
A swimmer moves forward because she pushes water ___.
backward
A 3-kg ball rolls at 6 m/s - what is it's momentum?
18
Which object has more PE: a 4-kg backpack at 1 m or a 2-kg backpack at 2 m?
Same
When friction increases, mechanical energy decreases because more energy becomes ___.
Heat
If mass increases and force stays the same, acceleration ___.
decreases
In a collision, the forces two objects exert on each other are ___.
Equal and Opposite