another physics problem that i dont understnad..
posted by brittany on .
An 58.0 N box of clothes is pulled 5.2 m up a 30.0° ramp by a force of 95 N that points along the ramp. If the coefficient of kinetic friction between the box and the ramp is 0.22, calculate the change in the box's kinetic energy.

The work done by the applied force is 95 x 5.2 = 494 J
Part of the work was done overcoming the friction force. The friction force is
Ff = 58*0.22*cos30 = 11.05 N and the work done against that force is 57.5 J
The work done increasing the gravitational potential energy is:
M*g*5.2*sin 30 = 150.8 J
That leaves a total of 494  57.5  150.8 J avaialbkle to increase kinetic energy 
your awesome! but where did you get the 95 in the first equation?

95 N is the pulling force, which they tell you. That multiplied bhy the distance pulled is the work done by that force.
Thanks for the kind words; you'd better check my numbers anyway. 
oh haha! sorry didn't see it

uhm where did you get 57.5? and what is M & g????

An 70.0 N box of clothes is pulled 24.0 m up a 30.0° ramp by a force of 115 N that points along the ramp. If the coefficient of kinetic friction between the box and ramp is 0.22, calculate the change in the box's kinetic energy.