# Mechanics Question. Car and van

1. May 18, 2008

### thomas49th

A breakdown van of mass 2000kg is towing a car of mass 1200kg along a straight horizontal road. The two vehicles are joined by a tow bar which remains parallel to the road. The van and the car experience constant resistances to motion of magnitudes 800N and 240N respectively. There is a constant driving force acting on the van of 2320N. Find:

a) The magnitude of the acceleration of the van and the car

Well the acceleration of the van and the car is going to be the same as they are joined together so:

using F = ma
2320-800-T=2000a
T-240=1200a

Rearrange to get T then sub into another equation

Giving a = 0.4m/s²

is that right???

b)find the tension in the tow bar

sub a into equation 2
T = 1200(.4)+240 = 720N

and it gives the same answer if you sub a into equation 1

Is that correct?

c) The two vehicles come to a hill inclinned at an angle of x to the horizontal, where sinx = 1/20. The driving force and resistances to motion are unchanged.

Find the magnitude of the acceleration of the van and the car as they move up the hill and state whether their speed increases or decreases

I will presume the hill is smooth, so friction can be ignored

There is going to be a downward force of 3200gSinx which can be simplified to 160g so this means the speed will decrease. But as for the magnitude im stuck....

Can someone please show me where to go

Thanks