Physics General Knowledge Questions: Physics GK Question for Competitive Exams
When milk is churned, the butter separates from it, what is the reason for this?
(A) Gravitational force
(B) Frictional force
(C) Centrifugal force
(D) Heat
Correct Answer : C
Explanation :
When milk is churned, the cream is separated from it due to centrifugal force because this force acts in an outwards direction. Due to this outward force, the heavier particles in milk experience more force than the lighter particles. The cream part, being heavier, separates from the milk and gets churned out.
Which of the following does not have kinetic energy?
(A) fired bullet
(B) Spring energy
(C) moving hammer
(D) flowing water
Correct Answer : B
Explanation :
Spring energy is the energy stored in a spring when it is expanded or contracted by using an external force. This is stored as elastic potential energy and is not a form of kinetic energy.
Does oil rise in the wick of the lamp because?
(A) the oil is too light
(B) due to capillary action
(C) due to decrease in surface tension
(D) oil is volatile
Correct Answer : B
Explanation :
The correct answer is Capillary action. The oil in the wick of an oil lamp rises up due to capillary action. This effect is due to surface tension of liquids. The wick here acts as a capillary tube.
The hairs of the shaving brush stick together after coming out of the water, what is the reason for this?
(A) Friction
(B) Surface tension
(C) Elasticity
(D) Viscosity
Correct Answer : B
Explanation :
When the brush is taken out of water, the hairs cling together due to surface tension. This happens because the free surface of water tries to acquire a minimum surface area.
If the length of the pendulum is made four times, then the time of swing of the pendulum?
(A) Decreases
(B) Becomes Four Times
(C) Becomes One Fourth
(D) Doubles
Correct Answer : D
Explanation :
Therefore we can say that time period is directly proportional to square root of length of the pendulum. Therefore as the length of the pendulum becomes four times, the time period becomes the 2 times.
The apparent weight of a person in a lift is less than the actual weight when the lift is moving?
(A) up with acceleration
(B) down at the same speed
(C) up with uniform speed
(D) down with acceleration
Correct Answer : D
Explanation :
The apparent weight of a body in an elevator moving with downward acceleration is given by N = m ( g – a ) . Thus, the apparent weight of the body is less than the actual weight of the body.
An ice cube is floating in a glass of water, when the ice melts, what will be the effect on the water level?
(A) will increase will decrease
(B) first increase then decrease
(C) will remain the same
(D) none of these
Correct Answer : C
Explanation :
When a floating piece of ice melts into water, it contracts by the volume equal to the volume of ice pieces above the water surface while floating on it. Hence, the level of water does not change when ice floating on it melts.
What are the changes in the molecules of an object when it is heated?
(A) the speed will increase
(B) weight will decrease
(C) the load will increase
(D) energy will decrease
Correct Answer : A
Explanation :
When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. The end result of increased molecular motion is that the object expands and takes up more space.
What happens to the temperature of water when it falls from a height?
(A) decreases
(B) increases
(C) neither decreases nor increases
(D) none of these
Correct Answer : B
Explanation :
The temperature of water increases when it falls from a height because when a water drop reaches the ground surface from a height, its potential energy increases.
What is the normal temperature of the human body?
(A) 65 degrees
(B) 95 degree
(C) 98.6°F
(D) 99 degrees
Correct Answer : C
Explanation :
Normal body temperature is considered to be 37°C (98.6°F); however, a wide variation is seen. Among normal individuals, mean daily temperature can differ by 0.5°C (0.9°F), and daily variations can be as much as 0.25 to 0.5°C.
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Rajesh Bhatia
A Writer, Teacher and GK Expert. I am an M.A. & M.Ed. in English Literature and Political Science. I am highly keen and passionate about reading Indian History. Also, I like to mentor students about how to prepare for a competitive examination. Share your concerns with me by comment box. Also, you can ask anything at linkedin.com/in/rajesh-bhatia-7395a015b/.
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