Kinetic & Potential Energy
What are the units for Energy?
joules (J)
What are BOTH formulas for Work?
W = Fd
W = ΔE
What is mechanical energy?
The total amount of energy in a system.
What are the units for Power?
watts (W)
What are the units for energy?
joules (J)
How much kinetic energy will a 1000kg car have travelling at 25m/s?
625 000 J
How much work is done lifting a 4 kg mass up to a height of 1.5 m?
60 J
At the top of a hill, a car at rest has X amount of energy. How much kinetic energy will be at the bottom of the hill, if all friction forces are ignored?
X
How is efficiency measured? (units)
Percent (%)
What LETTER represents energy lost due to friction?
Q
Mr. Tom walks up the stairs to an Year 11 class. The third floor is 18 m above the tennis courts. If Mr. Tom has a mass of 71 kg, how much potential energy does he have? (relative to the tennis courts)
12,780 J
An 80 kg box is pushed 8 m across a horizontal surface by a 45 N horizontal force. How much work was done?
360 J
A 1.2 kg ball is thrown vertically upward with an initial kinetic energy of 25 J. How high will the ball rise?
2.1 m
What is the power output of a 60 kg person who climbs a 5 m stair case in 15 seconds?
200 W
The total energy of a roller coaster at the top of hill is 4740 J. If the total energy is 2720 at the bottom of the hill, how much energy was lost due to friction?
2020 J
A 10 kg watermelon is thrown vertically upwards with an initial velocity of 7.0 m/s. How much kinetic energy will the watermelon have?
245 J
A 1500 kg car accelerates from a speed of 5 m/s to 12 m/s over a distance of 250 m. Neglecting friction, how much work was done to accelerate the car?
89,300 J
A 1 kg ball is dropped from the top of a building. Just before striking the ground, the ball’s speed is 12 m/s. What was the ball’s gravitational potential energy at the instant it was dropped?
72 J
A machine rated at 2500 W lifts a 155 kg object 60.0 m vertically in 1.0 minute. What is the efficiency of this machine?
62%
A 22 kg child slides down a ramp. At the bottom of the 5 m high ramp, the child has speed 2.50 m/s. Find the energy lost due to friction.
1030 J
Ryan and Alex have the same mass. Ryan is running at twice the speed of Alex. How does Ryan’s kinetic energy compare to Alex’s?
4 times Alex
A 1200 kg car is moving at 50.0 km/h. The driver applies the brakes and the car stops after 16 m. What is the force of Friction on the car?
7250 N
A 500 kg roller coaster is moving at 1.20 m/s at the top of a 30 m high hill. Assuming no friction, what will be the speed of the coaster when it zooms down the hill and is at height of 15 m?
17 m/s
A girl pulls a 5.0 kg wagon with a force of 20 N for 7.0 m. If the final speed of the wagon is 3.5 m/s, determine the efficiency of this process.
22% to 2 s.f.
or 21.9% to 3 s.f.
A 500 kg roller coaster is moving at 1.20 m/s at the top of a 30 m high hill. If 80 kJ is lost to heat, what will be the speed of the coaster at the bottom of the hill?
17 m/s to 2 s.f
or 16.8 m/s to 3 s.f.