Question

1) An object of mass 40kg is raised to a height of 5m above the ground. What is its potential energy if the object is allowed to fall, find its kinetic energy when its halfway down.
2) If the work done is 20 joule and displacement is 2m, then find the force applied.
3) A cubical block of mass with each side 10cm is lying on a table. The pressure exerted by block on the table is? (Assume G=10m/s)
4) The momentum of an object of mass 'm' moving with a velocity 'v=mv'.


Please answer ASAP.

Answer 1

ANSWER
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A1)
Mass of body = 40 kg
Height = 5 m
Potential Energy = mgh

Assuming g = 10 m/sec^2

=> Potential Energy = ( 40 × 10 × 5 ) J

=> Potential Energy = 2000 J

At halfway down,
Potential Energy converted into Knietic energy = m g ( h - h/2 )

= 40 × 10 × ( 5 - 5/2 )

= 40 × 10 × 2.5

= 1000 J = Energy converted which is equal to Kinetic energy

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A2)

Work = Force × Displacement

Force = Work / Displacement

=> Force = 20/2

=> Force = 10 N
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A3)
Let the mass of cubical block be mass

Area of the base of block = l × b
= 10 × 10 = 100 cm^2
Since 1 m^2 = 10000 cm
100 cm^2 = 1/100 m^2

Weight of block ( Force exerted downward ) = mg
= 10 × mass

Pressure = Force/Area

=> Pressure = 10 × mass ÷ 1/100

=> Pressure = ( 1000 × mass ) Pascal
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A4)
Mass = m
Velocity = mv

Momentum = mass × velocity

=> Momentum = m × mv

=> Momentum = m^2 × v

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HOPE IT HELPS ^_^
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