PDA

View Full Version : Help on problem


psruler
Feb18-04, 09:42 PM
Can anyone help me on two problems of my hw?

1) A tow rope is used to pull a 1050-kg along a level road, initially accelerating it from rest at 1.50m/s^2 for a duration of 12.0seconds. Calculate the magnitude of the tension force in the rope during this acceleration.(ignore friction in the problem)

My answer was 394N but i want to make sure if that was correct.

2) As a stoplight is approached, the person riding in the towed car applies the brakes and brings it to a stop in an additional 5.00s. Calculate the magnitude of the force of the brakes on the car, assuming the brakes are applied evenly so that the deceleration is constant.

NateTG
Feb18-04, 11:02 PM
Regarding question 1:

This is clearly an "F=ma" question. A mass of 1050 KG and an acceleration 1.5 m/s^2should give a force of at least 1500N

Question 2:
There's a bunch of ways to do this one. One of the easiers ways is to use v=at to find the starting velocity, and then the force in a similar fashion. Clearly the force here is larger than the force for question 1.

psruler
Feb18-04, 11:38 PM
Ok, I got the initial velocity for ques.2 and where do I go from there?

NateTG
Feb19-04, 12:13 AM
The change in velocity is equal to the acceleration multiplied by the time. You know the change in velocity, and the time, so that should give you the acceleration.

psruler
Feb19-04, 12:30 AM
wouldn't that give me an acceleration of 1.5 again?

psruler
Feb19-04, 12:38 AM
Ok i got it. thanks NateTG for your help!