Pulling Horizontally: Force Problems - Help Needed

[avb203796]

Please Help! (Force Problems)

Pulling horizontally on a rope moves a block with a total mass of 175.0 kg. If the coefficient of static friction between the block and the ground/slope is 0.12, what force must be applied to the rope to start the sled moving? If a second identical block is tied to the first block, and both are pulled with a force of 250.0 N, what acceleration will both experience, if the coefficient of kinetic friction is 0.10? Please help! I do not really understand how to approach this problem because I am having understanding forces.

 

[Chi Meson]

Part one: what is the weight of your block?

 

[neo143]

First part
Limiting force will be static friction * N = static friction * mg
that you can easliy calculate
Second part
Net force in the direction of motion will be
250 -kinetic friction* (N1 + N2)
= 250 -0.10(m1g + m2g)
= (m1 + m2) a
if you know m 1 and m2 ...you can easily calculate acceleration.

enjoy