Physics F=ma

[HappyRonald]

Can anyone help me to solve these questions ?
http://img847.imageshack.us/img847/7501/99151488.th.png (http://img847.imageshack.us/i/99151488.png/)

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[unsolvedcryptex]

For the first picture,

net F =ma
2g-1g = (2+1)a
a=10/3ms^-2

To solve it, you should take the larger weight minus off the lesser weight, then equal them to the total mass of the system multiply by acceleration.

I know this seems to be unnecessary, assuming that you are still in SPM, it's important to note that the pulley should be smooth so that the tension on the string on both the weight is the same.

For second pic,

net Force = ma
80-5g =5a
a=6ms^-2

I use g=10ms^-2

[Nicholasng925]

g = 9.81 ms^-2.

[henry_yew]

While in Physics you would use g = 9.81 m/s^2, in engineering practice however, we take g = 10 m/s^2 for one good reason: anything about engineering is, at best, an estimation. We don't look too closely on a difference of just 2%.