Question

In: Physics

Calculate the final speed of an object if its initial speed is 10 m / s....

Calculate the final speed of an object if its initial speed is 10 m / s. The object has a mass of 5 kg. Initially it has a height of 20 meters, and it goes down to a height of 15 m. There are no dissipative forces on the object.

Solutions

Expert Solution

By work-energy theorem, change in potential energy U = change in kinetic energy K

change in potential energy U = mgh

where m is mass, g is acceleration due to gravity and h is height difference between final position and

initial position

change in kinetic energy K = (1/2)m( vf2 - vi2 )

where vf is final speed and vi is initial speed

mgh = (1/2)m ( vf2 - vi2 )     or   ( vf2 - vi2 ) = ( 2 g h ) = ( 2 9.8 5 ) = 98 m2s-2

vf2 = vi2 + 98 = 100 + 98 = 198

hence final speed vf = = 14.07 m/s


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