Question

A football player at practice pushes a 60 kg blocking sled across the field at a constant speed. The coefficient of kinetic friction between the grass and the sled is 0.30.
How much force must he apply to the sled?

A. 18 N

B. 60 N

C. 180 N

D. 600 N

Answer 1

Answer:

C. 180 N

Explanation:

$m$ = mass of the blocking sled = 60 kg

$\mu$ = Coefficient of kinetic friction = 0.30

$f$ = kinetic frictional force acting on the sled

kinetic frictional force acting on the sled is given as

$f = \mu mg = (0.30) (60) (10) = 180 N$

$F$ =Force applied

For the sled to move at constant speed, the applied force must be same as the frictional force

$F = f\\F = 180 N$