1) To what height can a 499 W engine lift a 70 kg mass in 2 seconds? Height = XX
ID: 1413724 • Letter: 1
Question
1) To what height can a 499 W engine lift a 70 kg mass in 2 seconds?
Height = XXX Number meters
2) A speedboat must develop 110 horsepower in order to move at a constant speed of 53 mph through the water. What is the average resistive force through the water?
Avg Resistant Force = XXX pounds
3) A 2.2 kg ball travels from left to right at 10 m/s. A bat drives the ball in the opposite direction with a velocity of 18 m/s. If the time of contact was 0.1 seconds, what was the average force on the ball?
Average Force = XXXX Newtons
Explanation / Answer
1.
Power = work/time
Power = 499 W
work = m*g*h
m = 70 kg
h = Power*t/(m*g)
h = 499*2/(70*9.81)
h = 1.45 m
2.
Force = power/velocity
Power = 110 hp = 80904.86 W
velocity = 53 mph = 23.69 m/sec
Force = 80904.86/23.69 = 3415.14 N
F = 3415.14 N = 767.75 Pounds
3.
m = 2.2 kg
u = +10 m/sec
v = -18 m/sec
using momentum conservation
F*dt = m*u - m*v
F = 2.2*(10 - (-18))/0.1
F = 616 N
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