Q1. A cricket player while taking a catch lowers his hands to
(a) Increase time to impulse
(b) Decrease time of impulse
(c) Take catch safety
(d) Increase the area of impact
Q2. Where should be the center of gravity of a body?
(a) It must lie within the body
(b) It may be near but not essentially within the body
(c) It changes its position from time to time
(d) It must be outside the body
Q3. When a body is taken from the earth to the moon:
(a) Its weight increases
(b) Its weight decreases
(c) Its weight remains unchanged
(d) It because completely weightless
Q4. Kinetic energy of a body is directly proportion to its
(a) Weight
(b) Speed
(c) Mass
(d) Velocity
Q5. Thermal energy is an energy due to
(a) Kinetic energy of molecules
(b) Potential energy of molecules.
(c) Both (a) and (b)
(d) None of these
Q6. Power is measured in
(a) Joules per second
(b) Joules per minute
(c) Joules per square second
(d) None of these
Q7. Expansion during heating:
(a) Occurs only in a solid
(b) Increase the weight of a material
(c) Decrease the density of the material
(d) Occurs at the same rate for the liquids and solids
Q8. Melting point of ice:
(a) Increases with increasing pressure
(b) Decrease with increasing pressure
(c) Is independent of pressure
(d) Is proportional to pressure
Q9. If the door of a refrigerator is opened while connected to supply, the room gets:
(a) Cooled
(b) Heated
(c) No effect
(d) Nothing could be said as the temperature is not given
Q10. Heat is transmitted from higher to lower temperature through actual mass motion of the molecules in:
(a) Conduction
(b) Convection
(c) Radiation
(d) All the above three
S1. Ans.(a)
Sol. A cricket player while taking a catch lowers his hands to stop the momentum of the ball slowly.
S2. Ans.(c)
Sol.
S3. Ans.(b)
Sol. When a body is taken from the earth to the moon its weight decreases as the value of gravity on the surface of the moon is 1/6th as that of the earth’
S4. Ans.(c)
Sol.
S5. Ans.(c)
Sol. Heat energy is actually made up partly of kinetic energy and partly of potential energy.
S6. Ans.(a)
Sol. The unit of power is joules per second or J/s.
S7. Ans.(c)
Sol. Solids, liquids and gases all expand on being heated as result density (= mass/volume) decreases.
S8. Ans.(b)
Sol.
S9. Ans.(b)
Sol. If you leave the door open, heat is merely recycled from the room into the refrigerator, then back into the room. A net room temperature increase would result from the heat of the motor that would be constantly running to move energy around in a circle.
S10. Ans.(b)
Sol. The transfer of energy between an object and its environment, due to fluid motion. The average temperature is a reference for evaluating properties related to convective heat transfer.
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