boats us towing
PHYSICS Force and Power Question?
A) The graph shows the speed as a function of time for a minivan, coasting in neutral along a straight, level road, loaded with windsurfing equipment and towing a boat. The total mass is 2500kg (weight = 5512lbs). Find the size of the force due to wind and rolling friction when the van speed is 47.00mph (1mph= 0.447m/s).
HERE IS THE GRAPH:
http://img120.imageshack.us/img120/2104/minivandy9.gif
B) How much net power, in hp (1 hp=746W) must the engine deliver to maintain a speed of 47.00mph (21.01m/s) (Neglect losses involved in delivering the power).
A) I took a secant line from 10-15 seconds and another one from 15-20 seconds.
They were -0.8mph/s and -0.7344mph/s
Then I averaged them and got -0.7672mph/s.
That gives a tangent of -0.3429384 m/s^2
F = ma = 2,500kg(-0.3429384m/s^2) = -857.346N
B) To counteract that force, you need 857.346N(21.01m/s) = 18,012.84 watts
So 24.146 Horsepower.
ps. I’m not very confident that I used the best method on the first part. I’ll star it and see if anybody takes a look at it.
tow boat us 2