Advertisements
Advertisements
प्रश्न
A girl with having a mass of 35 kg sits on a trolley of mass 5 kg. The trolley is given an initial velocity of 4 m s–1 by applying a force. The trolley comes to rest after traversing a distance of 16 m. (a) How much work is done on the trolley? (b) How much work is done by the girl?
Advertisements
उत्तर
Effective mass of girl + trolley system = mass of girl + mass of trolley = 35 kg + 5 kg = 40 kg
Here, u = 4 10m s−1, v – 0, s = 16 m
Using v2 – u2= 2as, we get
a = `("v"^2 - "u"^2)/(2"s")`
= `(0 - 4^2)/(2 xx 16)`
= `(-1)/2 "m s"^-2`
∴ Force, F = ma = `40 xx ((-1)/2)"N"`
= −20N
(a) Work done on the trolley = – Work done by the trolley
= − Fs
= – (–20 N) × (16 m)
= 320 J
(b) As the girl keeps sitting on the trolley, there is no displacement in her position with respect to the trolley, so no work is done by the girl.
APPEARS IN
संबंधित प्रश्न
Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?
A ball of mass 0.20 kg is thrown vertically upwards with an initial velocity of 20 m s-1. Calculate the maximum potential energy it gains as it goes up.
State whether the object possess kinetic energy, potential energy, or both :
A man climbing a hill _____________.
Fill in the blank with suitable word :
The ability of a body to do work is called __________. The ability of a body to do work because of its motion is called __________.
Give two examples where a body possesses both, kinetic energy as well as potential energy.
Describe the energy changes which take place in a radio.
When an object falls freely towards the earth, then its total energy :
A microphone converts :
In the case of negative work, the angle between the force and displacement is
A body of mass 10 kg at rest is acted upon simultaneously by two forces 4 N and 3 N at right angles to each other. The kinetic energy of the body at the end of 10 s is
