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I am self studying for my GCE for the past 6 months now. I have been doing revision for a long time and did some question papers. I have a few problems and hope the people here can guide me. Thank you

Problem 1.

## Homework Statement

A 5.0kg mass is suspended from the ceiling. A horizontal force F is applied to hold the string in position as shown

http://i.imgur.com/ZdR72ff.jpg

Determine the reading of F on the spring balance by using a scale diagram

## Homework Equations

None

## The Attempt at a Solution

http://i.imgur.com/2KO2AnT.jpg

Am I doing it correctly?

It doesn't really make sense to me. I can't determine the force F. I only have 30degree angle and the weight.

Problem 2

## Homework Statement

A ladder weighing 200N is being held by a man. The man shoulder acts as a pivot. His arm is pushing an upward force F.

http://i.imgur.com/dMrcRtK.jpg

Where could a weight of 150N be hang upon, so that force F do not need to counteract the weight of the ladder

## Homework Equations

Moment= F x Perpendicular Distance

## The Attempt at a Solution

I am not sure if I am understanding it correctly. If I am not wrong, the question is asking me, where can I hang a weight of 150N, so that force F no need to counteract the weight of the ladder. Meaning, assume force F = 0N.

Let the distance be x

Total clockwise moment = total anti clockwise moment

150x = 200*0.5

150x = 100

x = 2/3

= 0.667m.

Therefore it needs to be hang 0.667m away from the pivot or at 3.167m of the ladder.

Am I understanding this correctly?

Problem 3

## Homework Statement

The figure shows 2 terminals M and N of a potential divider connected to a 6V battery. The circuit is connected to a Cathode-ray Oscillator.

http://i.imgur.com/zeV2e3j.jpg

(a) Describe in details what happens as the terminal is moved at a uniform speed from N to M.

(b) Draw the final reading of the final trace that is shown the CRO as N is moving towards M.

## Homework Equations

None

## The Attempt at a Solution

(a) As terminal N is moving towards M, there will be an increased in e.m.f, the results in a higher reading on the tracd

(b) http://i.imgur.com/bldLWjF.jpg

This is my attempt.

Please correct me if I make any mistakes thank you.

Theoretical Problem:

Is the work done the same if I move an object vertically upwards of height 2.0m v.s moving up a ramp at height until it reaches 2.0m?

From what I memorise, they are the same. Am I right? But can someone explain why? I want to understand why.

Thank you!