Test: The Concept of Potential Energy (June 28) - NEET MCQ

From the law of conservation of mechanical energy, the potential energy of a body at height h is converted into kinetic energy when it falls down. So, the magnitude of kinetic energy just before hitting the ground is equal to the potential energy at height h which is mgh.

Force between two stationary mass is gravitational force which is conservative. between two charge is electrostatic. muscular force is non conservative because we did work it lost or appear in form of heat and we need to eat food to gain energy for work done.

According to Newton's third law of motion, the force exerted on the floor by the person is equal and opposite the force exerted on the person by the floor.
According to the second law of Newton's law of motion, the net force exerted on the person is equal to the person’s mass times the person’s acceleration.
The net force exerted on the person = Force exerted by the floor+ Force exerted by gravity.
If the elevator goes up with acceleration g, the same is the person inside the elevator.
The work done on the man by the floor is the sum of the change in potential energy and kinetic
energy.
i.e W = Δ P.E + Δ K.E
But the elevator moves at a constant speed, so K.E =0.
W = Δ P.E
The work performed on you by the elevator is force times displacement = -Mgh
Negative sign shows it is moving upwards, i.e., against g.
 

F=k x (compression in string).
X=L.
a=LT^-2.
F=ma.
ma= k L.
LT^-2/L=k/m.
T^-2=k/m.

Change in GPE (Gravitational Potential energy) = mass x gravity x change in height
500 = 10 x 10 x change in height 

500 / 100 = change in height 

So, height from where it begins its dive = 5 m

mass = 50 x 100 = 5000 kg, g = 10 m/s²,  h = 10 m
Potential energy gained = mgh = 5000 x 10 x 10 = 5 x 10⁵ J

As the final velocity after the action of all forces is 0, therefore the person has 0 net acceleration.

And, as we know that

F_net = m.a_net

_{Therefore, the net force is 0 and hence, the net work done is also 0.}

Potential Energy is any type of stored energy. It can be chemical, nuclear, gravitational, or mechanical. Kinetic Energy is found in movement. Nuclear power plants change the nuclear potential energy of uranium or plutonium into electricity too.

For a variable force, the work done can be expressed as a definite integral of force over displacement for any system.In case of a variable force, the is calculated with the help of integration. For example, in the case of a spring, the force acting upon any object attached to a horizontal spring can be given as Fs = -kx, where k is the spring constant and x is the displacement of the object attached. We can see that this force is proportional to the displacement of the object from the equilibrium position, hence the force acting at each instant during the compression and extension of the spring will be different. Thus, the infinitesimally small contributions of work done during each instant are to be counted in order to calculate the total work done.