Work (yes or no)
You push on a wall as hard as you can, but the wall does not move. Is work being done?
No — there is no movement, so no work is done.
Kinetic energy is the energy of __________.
motion
Potential energy is the energy an object has because of its __________.
position
Work
A student pushes a box with a force of 20 N for a distance of 3 m. How much work is done on the box?
60 J
When you lift a book from the floor to a shelf, you are doing __________ on the book.
Work
You lift a backpack from the floor to the table. Is work being done?
Yes — you apply a force and the backpack moves in the direction of the force.
A moving object has kinetic energy. The faster it moves, the __________ its kinetic energy.
greater
Gravitational potential energy increases when an object’s __________ increases.
height
Potential Energy
A 4‑kg backpack is lifted to a shelf that is 2 m high. Use g=9.8 m/s2. What is the backpack’s gravitational potential energy on the shelf?
78.4 J
A rock sitting at the top of a cliff has a lot of __________ energy because of its height.
Potential
You hold a heavy box still above your head. Is work being done?
Answer: No — even though you feel tired, the box is not moving.
If an object is not moving, its kinetic energy is basically __________.
Zero
A book on a high shelf has more potential energy than a book on a low shelf because it is __________ from the ground.
higher
Kinetic Energy
A ball with a mass of 0.5 kg is moving at 6 m/s. What is its kinetic energy?
9 J
A moving skateboard has __________ energy because it is in motion.
kinetic
A grocery cart rolls down a ramp without anyone touching it. Is work being done?
Answer: Yes — gravity is doing work because it causes the cart to move
A bowling ball and a tennis ball roll at the same speed. The bowling ball has more kinetic energy because it has more __________.
mass
A stretched rubber band has potential energy because it is __________.
stretched
Work → PE
A student does 150 J of work to lift a box straight up. How much potential energy does the box gain?
150 J of Potential Energy
As a roller coaster goes down a hill, its potential energy decreases while its __________ energy increases.
kinetic
You carry a heavy suitcase across the room at a constant height. Is work being done on the suitcase?
Answer: No — your force is upward, but the suitcase moves horizontally, so the force and motion are not in the same direction.
When an object speeds up, its kinetic energy increases. When it slows down, its kinetic energy __________.
decreases
When potential energy decreases as an object falls, its kinetic energy __________.
increases
KE Change
A 2‑kg cart increases its speed from 3 m/s to 5 m/s. What is the change in kinetic energy?
Initial KE: 12×2×32=9 J
Final KE: 12×2×52=25 J
Change in KE = 25−9=
16 J
When you push a box and it starts moving, your force causes motion in the same direction. This means you have done __________ on the box, increasing its energy.
work