help out!!

.
A block of mass m is pushed towards a movable wedge of mass nm and height h with a velocity u. All surfaces are smooth. The minimum value of u for which the block will reach the top of the wedge is...
a> √2gh
b> n√2gh
c> √2gh(1+1/n)
d> √2gh(1-1/n)

10 Answers

3
Swastika dutta ·

hello!!! anyone plz help me out with this problem.

1
Bicchuram Aveek ·

The question's done but first assure if the wedge is fixed or not..........bye for now...rath's tuition ...no time to post soln.......i can post it tonight.

62
Lokesh Verma ·

First use conservation of linear momentum...

During this period mu=(M+m)V

you get the final v in terms of u (v here is in the horizontal direction)

Now conserve energy.. to take mgh+ 1/2 (m+M) (v2) = 1/2 m u2

Can you solve now?

3
msp ·

sir i have a dbt in ur momentum conservation,bcos there is no friction

1
arpan sinha ·

I think my procedure is correct.But ask Nishant bhaiya to check my ans.....
here is the ans..:
let v is the final velocity of the system..

mu =( m+nm) v
v= u/(1+n).

1/2 u2= 1/2 (1+n) v2+ gh
now put the value v=u/(1+n)
then,
u2=(1+1n)2gh.
hence opt C is correct..

3
Swastika dutta ·

thank u nishant sir.............. I have got the answer. :)

1
Philip Calvert ·

then please post it here so that the thread can be closed swastika [1]

3
Swastika dutta ·

Considering nm=M
mu=(m+M)v
therefore, v=mu/M+m.................(1)

1/2(m+M)v2 +mgh=1/2(mu2).............(2)
putting (1) in(2)

1/2mu2-1/2{(mu)2}/(M+m) = mgh
Solving it...by replacing M=nm.

u2(1-[m/(nm+m)])=2gh
furthur solving it.
I am getting opt c is correct.

3
Swastika dutta ·

Is it right Philip?????????????????

62
Lokesh Verma ·

Yes swastika :)

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