Work
How much work is required to lift a 850kg object a distance of 15m?
124,950 J
A lady leaps from a burning building with a PE = 24,000J. What is her KE when she hits the safety pad at the bottom?
24,000J
What is the power output of a motor that does 100 J of work in 5 seconds?
20 W
What is the efficiency of a pendulum if the final kinetic energy is 1000 J and the initial potential energy was 2000 J?
0.50 or 50%
Define the Work-Energy Theorem
Work = change of Kinetic Energy
What is the kinetic energy of a ball thrown in the air at the peak of its path?
Zero
What is the power used while lifting a 20N box 3 m in 2 minutes?
0.5 W
If a system has an efficiency of 0.9 (90%), what is the output energy if the system had an input energy of 500 J?
450 J
If I push a box 5 m across a floor with a force of 30N with a 10 N frictional force working against it, how much work am I doing?
100 J
If a 50 kg skydiver jumps from a 100 m high ledge, what is their kinetic energy when they are halfway down?
24,500 J
If I generate 50 W of power in pedaling my bicycle in 50 s, how much work did I do?
2500 J
How high did someone start from if their parachute has an efficiency rating of 0.8 and they ending up moving at 5 m/s?
1.59 m
How much work was done in slowing a 75 kg car to a stop if it was moving at 60 m/s to start?
135000 J
How high do you need to lift a 40 N box to have a potential energy of 100J?
2.5 m
If Dr. Ward and Mrs. Collins both lift a 50 kg box up the same 2 m distance, how can Dr. Ward generate twice as much power?
By going twice as fast
What is the efficiency of a parachute system that starts at 80 m and ends up moving at 10 m/s for a 100 kg man?
.06 or 6%
What work is done in accelerating a 50 kg box from 5 m/s to 15 m/s?
5000J
How fast is a 75 kg basejumper moving after leaping from a 750 m ledge?
121.24 m/s
What is the power used by an 500 kg elevator moving at 6 m/s?
29400 W
If a parachute has an efficiency rating of 0.8 (80%), how fast will someone (75 kg) be moving after jumping off a 50 m bridge?
28 m/s