Please show work and try to explain the answer and also if you compute the answe
ID: 1281774 • Letter: P
Question
Please show work and try to explain the answer and also if you compute the answer please dont ROUND the answer!!!
1 ) A car of mass 1400 kg traveling at 20 m/s is at the foot of a hill that rises 100 m in 2.2 km. At the top of the hill, the speed of the car is 8 m/s. Find the average power delivered by the car's engine, neglecting any frictional losses I need answer in watts
2 ) After hitting a long fly ball that goes over the right fielder's head and lands in the outfield, the batter decides to keep going past second base and try for third base. The 60 kg player begins sliding 2.80 m from the base with a speed of 3.82 m/s. If the player comes to rest at third base, What was the coefficient of kinetic friction between the player and the ground?
3 ) A record was set for stair climbing when a man ran up the 1500 steps of the Empire State Building in 15 minutes and 25 seconds. If the height gain of each step was 0.2 m, and the man's mass was 70.0 kg, what was his average power output during the climb?
Explanation / Answer
W = mgH - 0.5*m(v2-u2)
W = 1400 * 9.8 * 100 - (0.5 * 1400 * 336)
= 1136800 J
The time taken by the car to go uphill is t = d / v(avg)
t = 2200 m / 14 m/s [v = (20+8)/2 ]
t = 157.14 s
The average power delivered by the car engine is P = W/t = 1136800 J / 157.14 s
P = 7234 W = 7.23 kW
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2) W = Kf - Ki
W = 0 - 1/2 m vi2
W = -1/2 * 60 * 3.822
= -437.77 J
W = -f d = - mu m g d
mu = -W / m g d = 437.77 / (60 * 9.8 * 2.8)
mu = 0.266
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3) power = work / time
work = m a * d = 70 * 9.8 * 0.2 * 1500 = 205,800 J
time = 15 * 60 = 900 + 25 = 925 s
Power = 205,800 / 925
= 222.49 W