What Velocity Does the Sled Reach After 5 Seconds?

[Phyzor]

OK I'm stuk on a physics question involving Newton's Laws of motion.

Question:

Boy gives his sister ride on sled by exerting force of 300 N[E].
Frictional resistance amounts to 200 N. If sister and sled have combined mass of 50 kg, and if boy starts from rest and pushes for 5 sec., find:

a) the sled's acceleration
b) velocity attained by sled in 5 sec.
c) distance traveled by sled in 5 sec.


PLZ try to help and show step by step solutions

Reply ASAP thanx

 

[jcsd]

It's not the policy here to do peoples homewrok, but I'll give you the relevant formulae:

F = ma, v = u + at, s = ½(u + v)t

F is force, m is mass, a is acceleration ,v is final velocity, u is intial velocity, s is displacemnet and t is time.

 

[Phyzor]

Reply

Wait, how do we find initial velocity?

Thanx for help.

 

[HallsofIvy]

We don't. But since the problem asked for the "velocity attained" (i.e. the increase in velocity), we can take it to be 0- that way the final velocity WILL be the increase in velocity.