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Physics: Post your doubts here!

asadalam

asadalam

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Abdul Hanan said:
View attachment 54950
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Momentum = mv
We need to find the velocities at the 2 instants mentioned.
As the golf ball reaches the surfaces after being dropped, all its potential energy is converted to kinetic energy.
½ mv12 = mgh1
Speed v1 as the ball reached the surface = √(2gh1)
Similarly, the kinetic energy of the ball just as it leaves the surface is converted to potential energy at height h2.
½ mv22 = mgh2
Speed v2 just as the ball leaves the surface = √(2gh2)
The direction of motion of the golf ball changes after hitting the hard surface, so the initial momentum should be added.
Total change in momentum = m (v2+v1)
Total change in momentum = m√(2gh1) + m√(2gh2)
Abdul Hanan said:
2009.
but if you haven't tried p11 2012 try that its a must do paper.
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Summer or winter?
 
Abdul Hanan

Abdul Hanan

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asadalam said:
Momentum = mv
We need to find the velocities at the 2 instants mentioned.
As the golf ball reaches the surfaces after being dropped, all its potential energy is converted to kinetic energy.
½ mv12 = mgh1
Speed v1 as the ball reached the surface = √(2gh1)
Similarly, the kinetic energy of the ball just as it leaves the surface is converted to potential energy at height h2.
½ mv22 = mgh2
Speed v2 just as the ball leaves the surface = √(2gh2)
The direction of motion of the golf ball changes after hitting the hard surface, so the initial momentum should be added.
Total change in momentum = m (v2+v1)
Total change in momentum = m√(2gh1) + m√(2gh2)

Summer or winter?
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Sorry didn't mention that its winter.
And thanks for the explanation.
 
Xtreamer

Xtreamer

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Ahmed Aqdam said:
Any idea why aluminium can sustain more plastic deformation than steel?
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While putting tension on the bar, they monitor the load it takes to stretch the bar and how much it stretches in the process. .

If you divide the load by the cross sectional area and then divide that by the amount it stretched by the original length, you get values for steel around 30 x 10^ 6 psi . This is called the modulus of the material. For aluminum, it's value is roughly 10 x 10 ^ 6 psi.

This means aluminum will break sooner if all things are equal.

Aluminum does not have as much stretch capability as steel. Aluminum usually breaks after a very low stretch percentage. 3-4 % . Ity's more brittle than steel. Choosing the right steel, it can stretch close to 20 % or higher .

Having a very thick aluminum part can be made to be stronger than steel.
 
Abdul Hanan

Abdul Hanan

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Xtreamer said:
I just did this one the Ans is A.....I think current wont pass there because there is a shorter route of less resistance available
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yes your reason seams correct.
i did it thinking that p.d across the 40ohm resistor zero so current also zero.
 
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