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Punjab (PTB) · Chapter test · Free

1st Year Physics Chapter 4 TestWork, Energy and Power

30 marks · 40 minutes · 21 questions. Covers: CHAP 4: Work, Energy and Power.

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1st Year Physics Chapter 4 Test

1st Year · Physics · Punjab (PTB)

Name: ____________Roll No: ________Class/Section: ________Date: ________Total marks: 30Time: 40 minutes

Q1. Multiple choice questions (Attempt all · 10 × 1 = 10)

  1. Work has dimensions like:

    1. Torque

    2. Momentum

    3. Velocity

    4. Power

  2. A ball is thrown upward. As it rises, its:

    1. K.E. increases, P.E. decreases

    2. K.E. decreases, P.E. increases

    3. Both K.E. and P.E. increases

    4. Both K.E. and P.E. remain constant

  3. The work done is said to be negative if:

    1. Work is always positive

    2. (eq) < 90o

    3. (eq) > 90o

    4. (eq) = 90o

  4. During free fall, the loss in P.E. is equal to:

    1. Loss in K.E.

    2. Gain in K.E.

    3. Total energy of the body

    4. Work done by friction

  5. The power is equal to dot product of force and:

    1. Displacement

    2. Acceleration

    3. Velocity

    4. Position vector

  6. If the reference level is taken at ground level, the absolute P.E. of a body at height h is:

    1. Zero

    2. mgh

    3. Negative

    4. Constant

  7. According to work-energy principle in a linear motion the work done on body is equal to:

    1. Change in K.E

    2. Change in P.E

    3. Zero

    4. Sum of K.E and P.E

  8. The height above the ground of a child on a swing varies from 0.5 m of his lower point to 1.5 m at his highest point. The maximum speed of the child is approximately:

    1. 1.5 ms-1

    2. 4.4 ms-1

    3. 9.8 ms-1

    4. Depends upon child's mass

  9. The work-energy theorem is applicable:

    1. Only for conservative forces

    2. Only when friction is absent

    3. For all types of forces

    4. Only in vertical motion

  10. The total work done by a gravitational force in a closed path is:

    1. Maximum

    2. Equal to change in K.E.

    3. Zero

    4. Negative

Q2. Short questions (Attempt any 6 of 8 · 6 × 2 = 12)

  1. Is work done by a variable force always positive?

  2. A ball of mass m is held at a height h1 above a table. The table top is at a height h2 above the floor. One student says that the ball has potential energy mgh 1 but another says that it is mg (h1+h2). Whi is correct?

  3. A body is being raised to a height H from surface of the Earth. What is the sign of work done by both (body and the Earth)? Justify.

  4. What is non-conservative force? Give two examples.

  5. Point out positions where gravitational potential energy is takes as zero.

  6. A girl drop a cup from a certain height, which breaks into pieces. what energy changes are involved?

  7. A force acts on a ball moving with 14 ms-1 speed and brings its speed to 6 ms-1. Has the force done positive or negative work? Explain your answer.

  8. On what factors does G.P.E depend?

Q3. Long questions (Attempt any 2 of 3 · 2 × 4 = 8)

  1. Explain how do P.E and K.E are inter-convertable.

  2. Define K.E and derive an expression for the same.

  3. A 75 watt fan is used for 8 hours daily fro 30 day. Find: (i) Energy consumed in electrical units. (ii) Electricity bill if one unit costs Rs. 22.5?