Question

A cart loaded with bricks has a total mass of 13.5 kg and is pulled at constant speed by a rope.The rope is inclined at 27.9 degrees above the horizontal and the cart moves 13mts on a horizontal floor.The co efficient of kinetic friction between ground and cart is 0.3.The acceleration of gravity is 9.8 m/s^2.How much work is done on the cart by the rope.

Answer 1

Work done by rope = W
= (rope force)*cos 27.9)*13 meters
= (friction force)*13 m

The rope force F is given by the equation

horizontal component of F
= friction force
(since there is zero acceleration)

F*cos27.9 - (M*g-Fsin27.9)*0.30 = 0

0.8837 F = (132.3 - 0.4679 F)0.30
(0.8837 F + 0.1404 F)= 39.69
F = ?
W = ?

Answer 2

Since it is moving at a constant velocity there is no acceleration, which means there is no force. The equation for work is force*distance. There fore the work done on the cart by the rope is zero.