Q1.
How much time will it take a a winch motor with a POWER of 10 horsepower to lift a 1300 kg crate straight up against gravity a distance of 10. (Conversion factor: 1 horsepower = 1 hp = 746 W)
Q2.
A ball with mass of 7.7 kg moving at 8 m/s collides elastically with a second ball that is initially stationary. If the second ball moves away at 2 after the collision, find the mass of the second ball.
Q3.
A 95 kg cyclist rolls down a hill that is 18 m high, starting at v = 2 m/s, and is travelling at 12 m/s at the bottom. Find the work done by friction/air resistance that slows her down.
Thanks!
So what is holding you back? Where are you getting stuck?
1. work in = force * distance moved in direction of force
power in = work in/time
2. first law. no change in total momentum
then
elastic collision means kinetic energy after = kinetic energy before
3. How much did potential energy m g h change ?
How much did kinetic energy (1/2) m v^2 change?
if some of the loss in potential energy did not result in kinetic energy, some got lost to friction
1. Po = 10*746 = 7460 Watts = 7460 Joules/s.
Work = F*d = Mg*d = 1300*9.8*10 = 127,400 J.
T = 127,400J. * 1s/7460J = ---S.
Q1.
To calculate the time it will take for the winch motor to lift the crate, we can use the formula:
Time = Work / Power
First, we need to calculate the work done by the winch motor. Work is given by the formula:
Work = Force * Distance
The force required to lift the crate against gravity is equal to its weight. Weight is given by the formula:
Weight = Mass * Gravity
In this case, the mass of the crate is 1300 kg, and the acceleration due to gravity is approximately 9.8 m/s^2.
Weight = 1300 kg * 9.8 m/s^2
Next, we need to calculate the distance the winch motor lifts the crate. The distance in this case is 10 m.
Now, we have all the information we need to calculate the work done by the winch motor:
Work = Weight * Distance
Now that we have the work, we can calculate the time it will take using the power of the winch motor. The power is given as 10 horsepower. Since we need to convert it to watts, we can use the conversion factor:
1 horsepower = 746 watts
Power = 10 horsepower * 746 watts/horsepower
Now we can calculate the time:
Time = Work / Power
Substituting the calculated values, we can find the answer.