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Physics: Post your doubts here!

M

Metallic9896

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Haya24 said:
Answer is B pleaase help
Click to expand...

Let's just apply each equation and see where it leads us.

1. m1u1 + m2u2 = m1v1 + m2v2

Take m1 as given mass m and m2 as given mass 4m
Take u1 as given velocity +u, take u2 as stationary = velocity is 0

mu + 0 = mv1 + 4mv2

mu = mv1 + 4mv2

mu = m(v1 + 4v2)

u = v1 + 4v2

We are trying to find out v1 in terms of u.

Since it's an elastic collission, we can also consider the relative velocities equation:

2. v1 + u1 = v2 + u2

u1 is u, u2 is 0

v1 + u = v2

So, u = v1 + 4v2 from first equation, and u = v2 - v1 from second equation.

Let's get rid of v2 by making

1. u - v1 = 4v2
2. (u - v1)/4 = v2 and u + v1 = v2

Thus, as v2 is subject of formula in both equations, we can equate the two equations as:

(u - v1)/4 = u + v1

then multiply both sides by 4

u - v1 = 4u + 4v1

now bring u and v1 each on their own sides

-5v1 = 3u

make v1 subject of formula by dividing both sides of equation by -5

v1 = -3u/5

Answer shuold be B, which is correct.

I hope I helped. Feel free to ask more via this thread or pm. I would love to assist. :D
 
H

Haya24

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Metallic9896 said:
Let's just apply each equation and see where it leads us.

1. m1u1 + m2u2 = m1v1 + m2v2

Take m1 as given mass m and m2 as given mass 4m
Take u1 as given velocity +u, take u2 as stationary = velocity is 0

mu + 0 = mv1 + 4mv2

mu = mv1 + 4mv2

mu = m(v1 + 4v2)

u = v1 + 4v2

We are trying to find out v1 in terms of u.

Since it's an elastic collission, we can also consider the relative velocities equation:

2. v1 + u1 = v2 + u2

u1 is u, u2 is 0

v1 + u = v2

So, u = v1 + 4v2 from first equation, and u = v2 - v1 from second equation.

Let's get rid of v2 by making

1. u - v1 = 4v2
2. (u - v1)/4 = v2 and u + v1 = v2

Thus, as v2 is subject of formula in both equations, we can equate the two equations as:

(u - v1)/4 = u + v1

then multiply both sides by 4

u - v1 = 4u + 4v1

now bring u and v1 each on their own sides

-5v1 = 3u

make v1 subject of formula by dividing both sides of equation by -5

v1 = -3u/5

Answer shuold be B, which is correct.

I hope I helped. Feel free to ask more via this thread or pm. I would love to assist. :D
Click to expand...
Thank you sooo much. I get itt Thanks a lottt.
 
S

syed babar

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Hi guys,
Any idea about the gt of AS physics.. considering P2 was easy and P1 was okayish.. what do you guys think the gt would be, also keeping in mind that is was 90 last year. Pardon my anxiety. Cheers!
 
nishant sapkota 123

nishant sapkota 123

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syed babar said:
Hi guys,
Any idea about the gt of AS physics.. considering P2 was easy and P1 was okayish.. what do you guys think the gt would be, also keeping in mind that is was 90 last year. Pardon my anxiety. Cheers!
Click to expand...
i think it would be around 91-93.If u look at 2016 o/n ,our p2 was tougher than it was and our p1 was far more tougher than it was.the only thing easier of ours than of 2106 o/n was p3.(p1=12,p2=22,p3=33 which i m talking about)
 
S

syed babar

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nishant sapkota 123 said:
i think it would be around 91-93.If u look at 2016 o/n ,our p2 was tougher than it was and our p1 was far more tougher than it was.the only thing easier of ours than of 2106 o/n was p3.(p1=12,p2=22,p3=33 which i m talking about)
Click to expand...
Yess but, 90 was in 2016 m/j not in o/n.. so shouldn't it be lesser than that?
 
Chilli tty

Chilli tty

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Guys can some please send me the physics revision guide second edition and the chem one for as and a level
 
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