Question

a weight of 200kg is repeatedly dropped freely from a height of 10m on the head of a pole of mass 50kg to push it into the ground. for every impact the pole penetrates 7cm into the ground. find the average resistance of the ground.


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Answer 1

Answer

here weigh of the first body is given as 200kg so taking g=10ms-2

m= 20

so with energy conservation mgh=1/2mv^2

which will be 2000 and then this energy should be equal to work done the energy lost is resistance of ground  now force can be calculated by rate of change of momentum that will be 200*1.414 +50 that is weight of pole

now

multiply force with 7 cm in si unit u will get work done = 17.5*1.414 =24.75 approx 25 now your work done is 25 and kE is 2000 so resistance = energy lost = KE- workdone= 1975

hope it is correct