A girl on a bike is moving at a speed of 1.40 m/s at the start of a 2.15 m high and 12.4 m long incline. The total mass is 57.0 kg, air resistance and rolling resistance can be modeled as a constant friction force of 41.0 N, and the speed at the lower end of the incline is 6.80 m/s. Determine the work done (in J) by the girl as the bike travels down the incline.

568.16J

Explanation:

V = 1.4 m/s

h = 2.15m

H = 12.4m

M = 57.0kg

Fr = 41.0N

Vb = 6.80m/s

g = 9.8m/s²

K.E at the top + P.E at the top + Work done = K.E at the bottom + frictional force.

½mv² + mgh + W = ½mVb + Fr.H

(½* 57 * 1.4²) + (57 * 9.8 * 2.15) + W = (½ * 57 * 6.8²) + (41 * 12.4)

55.86 + 1202.22 + w = 1317.84 + 508.4

1258.08 + w = 1828.24

W = 1826.24 - 1258.08

W = 568.16J

if they have a finite resultant

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it