1. Power - All mixed up
A 2340 kg car speeds up from 12 m/s to 25 m/s in 4.6 seconds on the level. What power?

2. Power - All mixed up
An elevator motor takes a 780 kg car and speeds it up from rest to 5.4 m/s lifting it 4.1 m in 1.51 s. Power = ?

3. Iwanna Ferrari stretches a 150 N/m spring a distance of 1. 35 m in
Iwanna Ferrari stretches a 150 N/m spring a distance of 1.35 m in .53 seconds. What is her average power output?
Eelas = 1/2kx2
Power = work/time = (1/2kx2)/t
1/2(150 N/m)(1.35 m)2/(.53 s) = W = 260 W
260 W

4. A 1520 kg car speeds up from 20. m/s to 30. m/s on the level
A 1520 kg car speeds up from 20. m/s to 30. m/s on the level. What time will it take with a 34 kW engine?
Ek = 1/2mv2
Change in energy = work = 1/2mv2 - 1/2mu2
= 1/2(1520 kg)(30. m/s)2 - 1/2(1520 kg)(20. m/s)2
work = 380,000 J
power = work/time, time = work/power =
(380,000 J)/(34,000 J/s) = s
11 s

5. A 1452 kg car is going 11. 0 m/s at the top of a 9. 20 m tall hill
A 1452 kg car is going 11.0 m/s at the top of a 9.20 m tall hill. What is the power output of the engine if it is going 22.0 m/s at the bottom of the hill 13.0 seconds later?
Total at top: = 1/2(1452 kg)(11.0 m/s)2 + (1452 kg)(9.8 N/kg)(9.20 m)
Total at top: = J
Total at bottom: = 1/2(1452 kg)(22.0 m/s)2 = J
Work = Change = J J = J
Power = work/time = ( J)/(13.0 s) = W = 10.2 kW
10.2 kW