MCQ : Work And Energy - 1
10 Questions MCQ Test Science Class 9 | MCQ : Work And Energy - 1
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If 1 newton of force displaces a body by 1 m, the work done is
One joule equals the work done ( or energy expended) by a force of One Newton (N) acting over a distance of one meter (m). One Newton equals a force that produces an acceleration of one meter per second (s) per second on a one Kilogram (Kg) mass. Therefore, one joule equals one Newton meter.
A load of 50 kg is pulled upward by 5 m. The work done by the external force is (g = 10 m/s2)
A mass is moving 5 m/s with speed of along the x-direction on a smooth surface, when a force of 5 N acts on it along they-axis. The work done by against the force is
as force is perpendicular to displacement.
An object of mass 1kg has a PE of 1J relative to the ground when it is at a height of:
Given:
Mass of the Body (m) = 1 Kg.
Potential energy (E) = 1 Joule.
Acceleration Due to Gravity (g) = 9.8 m/s²
Explanation:
Potential Energy:-
Potential energy is the energy which a body posses due to virtue of Position.
Formula of Potential energy
P.E = Mgh
M denotes Mass of the Body.
g denotes Acceleration Due to Gravity.
h Denotes the Height to which the body is raisen.
From Potential energy Formula,
⇒ P.E = Mgh
⇒ E = M x g x h
⇒ E = 1 kg x 9.8 m/s² x h meters
⇒ E = 1 x 9.8 x h
⇒ E = 9.8 x h
∵ [ Potential Energy = 1 joule.]
Substituting,
⇒ 1 = 9.8 x h
⇒ h = 1/9.8
⇒ h = 10/98
⇒ h = 0.102 Meters.
So, The Height at which Potential Energy is 1 joule is 0.102 meters.
A bullet entering a metal block of 30 cm length stops on reaching 25 cm. The energy with the bullet will be lost
A tank contains water of mass ‘m’ to a height ‘h’. The potential energy associated is
Height will be upto the centre of gravity of tank, so P.E. = mgh
Two particles of masses 1 g and 4 g have equal kinetic energies. What is the ratio between their momenta?
A force of 10 N displaces a body by 6 m in 3 seconds. The power of the agency applying the force is
We know, Power :-
= force * displacement/Time
Force is 10 N, displacement = 6 m
Time = 3 s
Then, power = 10*6/3 => 10 * 2 ⇒ 20W
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