# Homework Help: Force required to accomplish acceleration

1. Jan 24, 2012

### MMCS

A 200kg motorcycle accelerates uniformly from rest and attains a velocity of 60mph over a distance of 150m. Determine the force required to accomplish this increase in speed.

Any suggestions?

Thanks

2. Jan 24, 2012

### Delphi51

Find your list of formulas for accelerated motion. Pick one that doesn't have time in it, since you don't know and don't wish to find time. Or use two of them that do have time, find the time first, then the acceleration.

List of formulas: http://hyperphysics.phy-astr.gsu.edu/hbase/mot.html#motcon

3. Jan 24, 2012

### MMCS

I have converted 60mph to 26.8m/s

Then,

Distance/Velocity = time
150/26.82 = 5.59s

Then

Acceleration = change in velocity/time

Acc = 26.82 / 5.59 = 4.79m/s^2

Then

Force = Mass x Acc

4.79 x 200 = 959N

However, i have been given the answer to be 486N

4. Jan 24, 2012

### SammyS

Staff Emeritus
(I put that phrase in bold type.)

The time you got is the time it takes to go 150 meters at a speed of 26.82 m/s. The motorcycle is not traveling that fast until the very end of the 150 m.

5. Jan 24, 2012

### Delphi51

"Distance/Velocity = time" is not an accelerated motion formula. It is a constant speed or zero acceleration formula. Look for one in the list of constant acceleration formulas. It must have an "a" in it for acceleration. You want to find "a" so you can then get the force with F = ma.

6. Jan 25, 2012