Calculating Force Problems on Toy Car

[shenwei1988]

[SOLVED] force problems

A 7.79 kg toy car now starts at rest and is going around a circular track of radius 38.5 m, the accelerates at a constant rate to a final speed of 5.13 m/s in 6 seconds. At the instant it reaches its final speed, find:1.the magnitude of the inward force needed to keep it moving in a circle
2.the magnitude of the tangential force

F=ma
a=v2/r

question1. F=mv2/r=7.79(5.13)(5.13)/38.5=5.32. and that's is right.
question2. the magnitude of the tangential force, i don't know what to do with it ,can anybody help me?

 

[Dick]

The tangential force problem is the same as a linear force problem. 0->5.13m/sec in 6sec. How much force?

 

[shenwei1988]

thank you for help. i got the answer.