Advertisements
Advertisements
प्रश्न
A body of mass m is moving with a velocity v. Write the expression for its kinetic energy.
उत्तर
Assume that a mass-m body is travelling at a velocity of v. An opposing force, F brings it to rest.
Let a represent the force's uniform retardation, and let it travel a distance of S before coming to rest at T. Then,
The kinetic energy of the body = the work done by the retarding force in stopping it.
Kinetic energy = Force × displacement
= F × S ...(i)
Retarding force F = ma ...(ii)
Initial velocity u = v, final velocity v = 0
From the relation v2 = u2 +2aS
0 = v2 - 2aS (since a is the retardation)
∴ Displacement S = `v^2/(2a)` ...(iii)
Substituting the values of F and S from equation (ii) and (iii) in equation (i), we get
kinetic energy `K = F × S = ma × v^2/(2a) = 1/2 mv^2`
Kinetic energy = `1/2 ` mass × (velocity)2
APPEARS IN
संबंधित प्रश्न
Name the type of energy (kinetic or potential) possessed by the following:
A bullet fired from a gun.
State two disadvantages of producing electricity from solar energy.
Explain the principle of producing electricity using the nuclear energy.
State four ways for the judicious use of energy.
Write five forms of energy.
What kind of energy is possessed in a situation when?
A stone lying on the top of roof.
State the energy changes which take place when:
A bulb glows, when torchlight is switched on.
Show that in case of a body falling freely under gravity, total mechanical energy remains conserved (neglect air resistance).
Use your brain power!
How do we save fuel by using public transport?
