Posted by Leila on .
A 120kg crate, starting from rest, is pulled across a floor with a constant horizontal force of 400 N. For the first 17 m the floor is frictionless, and for the next 17 m the coefficient of friction is 0.34. What is the final speed of the crate?

PHYSICS HELP! 
drwls,
Kinetic energy gained during the frictionless interval is 400 N * 17 m = 6800 J. When there is friction, the net force pulling the weight is 400 N  M*g*mu = 400  399.8 N = 0.2 N. Additional kinetic energy gain is limited to 0.2N*17m = 3.4 J
The rest of the work done ends up as heat.
Final kientic energy is 6803 J. Use that for the final velocity 
PHYSICS HELP! 
Leila,
how would I show that in m/s?

PHYSICS HELP! 
HI,
you use 1/2*m*v^2

PHYSICS HELP! 
ahmed,
the answer is = 1