Asked by Kundan

A ball of mass 1 kg dropped from 9.8m height , strikes the ground and rebounds to a height of 4.9m .If the time of contact between ball and ground is 0.1s,then find impulse and average force acting on ball.
Answered by mala
26ns
Answered by JITIN SHARMA
Velocity when it hits the ground
u = sqrt(2gH)
= sqrt(2 * 9.8 * 9.8)
= 9.8 sqrt(2) m/s

Velocity just after hitting the ground
v = sqrt(2gH)
= sqrt(2 * 9.8 * 4.9)
= 9.8 m/s

Impulse = change in momentum
= mass × change in velocity
= m * (v - u)
= 1kg * (9.8 - (-9.8*sqrt(2)) m/s
= 9.8 * (1 + sqrt(2)) kgm/s
= 9.8 * 1.414 kgm/s
= 13.8572 kgm/s

Average Force = Impulse / Time taken
= 13.8572 / 0.1
= 1.38 N
Answered by RUHAN
Answer is wrong
Answered by Rishav
Answer is wrong..the correct answer is 23.89Ns, 238.9N
Answered by Janhavi
Answer is wrong..
Answered by Ruman
It's a wrong answer
Correct answer is 23.52Ns,235.2N
Answered by Sireesha
The answer given by kundan is almost correct.
But only at the last part where he solve:
9.8*(1+root2)= 9.8*(1+1.414)= 9.8*2.414=23.857
This is where he went wrong
Similarly we can fine force
Answered by Lovely
Thanks for correcting the mistake
Answered by Anonymous
Why has -ve sign being used in front of initial velocity ??
Answered by Anonymous
What is meaning if square root 2
Answered by addyy
Actually the correct answer is 23.89Ns and force is 238.9 N but how ? The solution is yet not cleared
Answered by Chitransh
......Question asked by Kundan......
Some favourite answers :
(1) 13.85 by Jitin Sharma
~ Wrong
(2) Correction of Jitin by Sireesha
He forgot to do the sum of √2 + 1
~ Okay
~ But How the (9.8 × 2.414) = 23.857
~ Wrong
(3) Chitransh
Last step -----> [9.8 × 2.414] = 23.657 N-s
Answered by Piyush kuldeep
This all answers are wrong the write answer is 23.52Ns 235.2.
Answered by Pragati..
Still if uh multiply 9.8*2.414
It comes out to 23.657 and not 23.857
But the answer given here in my material is 23.857
Answered by Shikha
Correct answer is 23.89ns,238.9n
Answered by Devika
If u assume gravity is 10 instead of 9.8 you will get 23.89.
Answered by heklo misyer
Sab ka galt h pata nahi kya padhte h sab k sab . Correct answeer is 9.8765 N
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