Hi all. Need guidance for some fundamentals physics.

lundi 30 juin 2014

Hi everyone.

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.

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

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



http://ift.tt/1oi9QJt



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



2. Relevant equations



None



3. The attempt at a solution



http://ift.tt/1qrhioS

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

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

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://ift.tt/1oi9QZL



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



2. Relevant equations

Moment= F x Perpendicular Distance



3. 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

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



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://ift.tt/1qrhggO



(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.



2. Relevant equations



None



3. 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://ift.tt/1oi9SB4

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!





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