M1 Mechanics question from a very old textbook

How do you work this out, step by step.

A miner's cage of mass 420kg contains three miners of total mass 280kg. The cage is lowered from the rest by a cable. For the first 10 seconds, the cage accelerates uniformly and descends a distance of 75m. Find the force in the cable during the first 10 seconds.

Thanks

Reply 1

ViralRiver

You want to work out for force in the cable, so you need mass and acceleration. You're given the masses, all you need now is acceleration. You should be able to use SUVAT for that.

Reply 2

Obscenedilemma

Original post by ViralRiver

You want to work out for force in the cable, so you need mass and acceleration. You're given the masses, all you need now is acceleration. You should be able to use SUVAT for that.

Is the tension 5810N and acceleration 1.5m/s^2 ?

(edited 12 years ago)

Reply 3

Klearcut

I got the same acceleration as you, however, my tension is 1050N :redface:

Reply 4

Obscenedilemma

Original post by Klearcut

I got the same acceleration as you, however, my tension is 1050N :redface:

yeah I 1050N too but I took it away from 6080N... but that's trying to find out the unbalanced force. I don't know why I did that.

I think you're right

(edited 12 years ago)

Reply 5

Meg8999

If you do 700 * (9.8-1.5) you get 5810N, because you need to consider acceleration due to gravity :smile:

Reply 6

MatrixOfficial

Original post by Obscenedilemma

How do you work this out, step by step.
A miner's cage of mass 420kg contains three miners of total mass 280kg. The cage is lowered from the rest by a cable. For the first 10 seconds, the cage accelerates uniformly and descends a distance of 75m. Find the force in the cable during the first 10 seconds.
Thanks

Sorry for the late reply but for anyone else wondering how to do this question, I will explain it.

First workout the downward force on the cage which is 420g+280g=6860
Then find a formula for the tension using acceleration (using newton's 2nd law)
6860-t=700a (Equation 1)

Then using s=ut+1/2at^2
sub t=10, u=0, s=75 to work out a which should be 1.5 m/s^2

Sub 1.5m/s^2 in equation 1 and the formula you should get is 6860-t=1050

Solve the equation to get t=5810N