Question

A 4 kg block is placed on a plane inclined at 30◦
. If the coefficient of the static friction
is 0.3 and the coefficient of kinetic friction is 0.2, what is the net force on the block?
(a) 0 N
(b) 9.4 N
(c) 12.8 N
(d) 19.6 N

Answer 1

@cormacpayne

Answer 2

Two objects are dropped from a height of 100 m. If one object is heavier than the
other object, which of the following is true? (Note: ignore air resistance)
(a) The heavier object will experience equal force and accelerate more slowly.
(b) The heavier object will experience more force and accelerate more quickly
(c) The heavier object will experience equal force and accelerate at the same rate
(d) The heavier object will experience more force and accelerate at the same rate.

I put B

and for the first one I put 0

Answer 3

@Vincent-Lyon.Fr

Answer 4

For the second question, they are going to accelerate at the same speed. The force of the larger object should be greater though since F = ma = mg.

Take a look at this article for more clarification on this topic:
http://www.wired.com/2013/10/do-heavier-objects-really-fall-faster/

Answer 5

In the first problem, it seems there is not enough static friction to keep the block from sliding. So net force will not be zero and the block will accelerate downwards.

Answer 6

I thought B is the best choice! what do you thik @cormacpayne

Answer 7

if the net force isn't 0 then what it is!

Answer 8

@Vincent-Lyon.Fr

Answer 9

do you think its d for the second The heavier object will experience more force and accelerate at the same rate.

Answer 10

@cormacpayne

Answer 11

@aaronq