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.
17 answers
26ns
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
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
Answer is wrong
Answer is wrong..the correct answer is 23.89Ns, 238.9N
Answer is wrong..
It's a wrong answer
Correct answer is 23.52Ns,235.2N
Correct answer is 23.52Ns,235.2N
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
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
Thanks for correcting the mistake
Why has -ve sign being used in front of initial velocity ??
What is meaning if square root 2
Actually the correct answer is 23.89Ns and force is 238.9 N but how ? The solution is yet not cleared
......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
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
This all answers are wrong the write answer is 23.52Ns 235.2.
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
It comes out to 23.657 and not 23.857
But the answer given here in my material is 23.857
Correct answer is 23.89ns,238.9n
If u assume gravity is 10 instead of 9.8 you will get 23.89.
Sab ka galt h pata nahi kya padhte h sab k sab . Correct answeer is 9.8765 N