Question

A sled whose total mass with cargo is 30.0 kg rests on ice. The coefficient of static friction is 0.20 and the coefficient of kinetic friction is 0.15 the sled is attached to a rope horizontally in which the tension force is slowly increased how much tension force applied by the rope will cause the sled to start moving?

A. 0 N
B. 9.8 N
C. 59 N
D. 290 N

Answer 1

when sled just start to move the force on the sled will be equal to the static friction

So here we need to find the value of static friction

We know that

m = 30 kg

`\mu_s = 0.20`

now we know that normal force on the block is counterbalanced by weight of the block

`F_n = mg`

`F_n = 30*9.8`

now in order to find the friction force we can use

`F_s = \mu_s * F_n`

`F_s = 0.20 * 30 * 9.8`

`F_s = 59 N`

so it requires 59 N of force to move the sled