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ICSE-VIII-Physics

04: Energy Class 8 Physics

with Solutions - page 2

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  • #2-g
    Kinetic energy = 1/2 × mass × ____
    Ans : Kinetic energy = 1/2 × mass × (speed)2
  • #2-h
    Power P = _____/time taken.
    Ans : Power P = work done/time taken.
  • #2-i
    The S.I. unit of power is ____
    Ans : The S.I. unit of power is watt
  • #2-j
    I H.P. = ____
    Ans : I H.P. = 746 W
  • Qstn #3
    Match the following
    Column A Column B
    (a) A stone at a height (i) power
    (b) A moving hall (ii) joule
    (c) Energy (iii) work done in 1s
    (d) Power (iv) potential energy
    (e) watt (v) kinetic energy
    Ans :
    Column A Column B
    (a) A stone at a height (iv) potential energy
    (b) A moving hall (v) kinetic energy
    (c) Energy (ii) joule
    (d) Power (iii) work done in 1s
    (e) watt (i) power
  • Qstn #4
    Select the correct alternative
  • #4-a
    The S.I. unit of work is
    1. second
    2. metre
    3. joule
    4. newton
    digAnsr:   3
    Ans :
    3. joule
  • #4-b
    No work is done by a force if the body
    1. moves in direction of force
    2. does not move
    3. moves in opposite direction
    4. none of the these
    digAnsr:   2
    Ans :
    2. does not move
  • #4-c
    Two coolies A and B do some work in time 1 minute and 2 minute respectively. The power spent is
    1. same by both coolies
    2. is more by coolie A than by B
    3. is less by coolie A than by B
    4. nothing can be said.
    digAnsr:   2
    Ans :
    2. is more by coolie A than by B
  • #4-d
    The expression of power P is
    1. P = mgh
    2. P = P = 1/2 Mv2
    3. P = F × d
    4. P = F × d/t
    digAnsr:   4
    Ans :
    4. P = F × d/t
  • #4-e
    I H.P. is equal to
    1. 1 W
    2. 1 J
    3. 746 J
    4. 746 W
    digAnsr:   3
    Ans :
    3. 746 W
  • #4-f
    When a boy doubles his speed, his kinetic energy becomes
    1. half
    2. double
    3. four times
    4. no change
    digAnsr:   3
    Ans :
    3. four times
  • #4-g
    A boy lifts a luggage from height 2 m to 4 m. The potential energy will become
    1. half
    2. double
    3. one-third
    4. one-fourth
    digAnsr:   2
    Ans :
    2. double
  • #
    Section : B
    Short/Long Answer
  • Qstn #1
    Define work.
    Ans : :
    When a force is applied on a body and there is displacement of the body, work is said to be done.
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