# Resultant force on the piston at the end of stroke

1. Jun 16, 2014

### kelvin macks

1. The problem statement, all variables and given/known data

my question is on part a , the ans is 4260N . but my answer is double of the ans given. why i'm wrong? the working is shown in the photo.

2. Relevant equations

3. The attempt at a solution

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2. Jun 16, 2014

### sankalpmittal

The net force acting in an SHM is F=-kx...

You can find k by using the formula of frequency of an SHM.

3. Jun 17, 2014

### dean barry

You've maybe put 0.12 m as the crank radius when it should be 0.06 m
r = crank radius = 0.06 metres
w = crank rotation rate = 376.99112 rad / sec

Find the tangential velocity (v) from :
v = w * r
v = 376.99112 * 0.06
v = 22.619 m/s (ANSWER b)

Find the centripetal acceleration (a) :
a = v ² / r
a = 8,527.338 (m/s)/s

The decelerating force (f) = m * a
f = 0.5 * 8,527.338 N
f = 4,263.67 N (ANSWER a)

4. Jun 17, 2014

### sankalpmittal

Dude, complete solutions aren't allowed here...