A body of mass 100 kg is lifted up by 10 m. Find

A body of mass 100 kg is lifted up by 10 m. Find

(a) The amount of work done.

(b) Potential energy of the body at that height (g =10 ms–2)

Ans: – The work done, w=F×S,

Here, f=m×a= 100×10=1000; s=10m.

So, w= 1000×10= 10^4 NS.

• Potential energy=mgh,

Here, m=100kg, g=10m/s^2, h=10m.

Potential energy= 100×10×10=10^4.

 

Why Road accidents at high speeds are much worse than the accidents at low speeds?

Ans: –  The most of the road accident now a days happen because of the high speed. As we know the kinetic energy is maximum when the speed is high and low when speed is low so more fatal damage happen in case of high kinetic energy.

 

Two bodies of equal mass move with uniform velocities u and 4 u respectively. Find the ratio of their kinetic energies.

Ans: – The kinetic energy=1/2mv^2;

So, kinetic energy id directly proportional to the velocity.

Ek (1)/Ek (2) =¼.

 

What would you like to prefer a ramp or a staircase to reach at the third floorof your hospital? Justify.

Ans: – We always try to do small amount of work for the purpose of working days. In this case as in ramp there is no way of doing heavy works and in stair case the we have to do more works so ramp is preferable.

 

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