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SCIENCE CLASS- 9

Class 9 Science Worksheets: Chapter-7

Chapter-wise worksheets with competency-based questions and board exam practice based on the latest CBSE syllabus.

CBSE Latest Syllabus Chapter-wise Worksheets

Worksheet

Chapter 7: Work, Energy and Simple Machines

Class: IX     Subject: Science (Physics)

Name: _______________________     Roll No.: _______________________

Date: _______________________     Marks: 50     Time: 60 Minutes


Section A : Multiple Choice Questions

Choose the correct answer.

  1. Work is said to be done when
    1. Only force acts
    2. Only displacement occurs
    3. Force causes displacement
    4. Object remains at rest

  2. The SI unit of work is
    1. Newton
    2. Joule
    3. Watt
    4. Pascal

  3. Which formula gives work done by a constant force?
    1. F = ma
    2. W = Fs
    3. P = W/t
    4. K = mv

  4. The energy possessed by a moving object is
    1. Potential Energy
    2. Thermal Energy
    3. Kinetic Energy
    4. Electrical Energy

  5. The formula for kinetic energy is
    1. mgh
    2. ½mv²
    3. Fs
    4. ma

  6. The formula for gravitational potential energy is
    1. ½mv²
    2. mgh
    3. Fs
    4. mv

  7. The SI unit of power is
    1. Joule
    2. Newton
    3. Watt
    4. Volt

  8. Power is defined as
    1. Force × Time
    2. Work × Time
    3. Work Done ÷ Time
    4. Energy × Force

  9. Mechanical energy is the sum of
    1. Heat and Light Energy
    2. Kinetic and Potential Energy
    3. Electrical and Chemical Energy
    4. Force and Power

  10. Which simple machine is used to draw water from a well?
    1. Pulley
    2. Wheel
    3. Screw
    4. Lever

Section B : Fill in the Blanks and True/False

Fill in the Blanks

  1. Work = __________________ × Displacement.
  2. The SI unit of energy is __________________.
  3. Kinetic Energy = __________________.
  4. Potential Energy = __________________.
  5. Power = __________________ ÷ Time.

Write True or False

  1. Work is zero if displacement is zero. __________
  2. Energy is the capacity to do work. __________
  3. Kinetic energy depends upon the velocity of the object. __________
  4. Mechanical energy is always destroyed during motion. __________
  5. Power is measured in Joules. __________

Section C : Match the Following

Column A Column B
1. Work A. Watt
2. Power B. mgh
3. Kinetic Energy C. Force × Displacement
4. Potential Energy D. ½mv²
5. Pulley E. Draws water from a well

Section D : Short Answer and Numerical Questions

  1. Define work.

  2. Differentiate between kinetic energy and potential energy.

  3. State the Work-Energy Theorem.

  4. What is mechanical energy?

  5. Define power and write its SI unit.

  6. A force of 40 N moves an object through 5 m. Calculate the work done.

  7. Calculate the kinetic energy of a body of mass 4 kg moving with a velocity of 6 m/s.

  8. Find the potential energy of a body of mass 5 kg placed at a height of 8 m. (Take g = 10 m/s²)

  9. A machine does 1200 J of work in 30 seconds. Calculate its power.

  10. A body of mass 2 kg falls freely from a height of 20 m. Calculate its potential energy at the top. (Take g = 10 m/s²)

Section E : HOTS and Case Study

Assertion and Reason

  1. Assertion (A): Work done is zero when there is no displacement.

    Reason (R): Work depends upon both force and displacement.
    1. Both A and R are true and R is the correct explanation.
    2. Both A and R are true but R is not the correct explanation.
    3. A is true but R is false.
    4. A is false but R is true.

  2. Assertion (A): Mechanical energy remains constant during free fall if air resistance is neglected.

    Reason (R): Potential energy continuously converts into kinetic energy.
    1. Both A and R are true and R is the correct explanation.
    2. Both A and R are true but R is not the correct explanation.
    3. A is true but R is false.
    4. A is false but R is true.

Case Study

A student lifts a school bag of mass 5 kg from the floor to a table of height 1.2 m. Later, the bag accidentally falls back to the floor. Assume g = 10 m/s².

  1. Calculate the work done by the student in lifting the bag.
  2. What is the potential energy of the bag on the table?
  3. What happens to the potential energy as the bag falls?
  4. Which form of energy increases while the bag is falling?
  5. Name the law illustrated by this energy conversion.

Bonus Challenge

A boy pushes a box with a force of 60 N through a distance of 8 m in 12 seconds.

  1. Calculate the work done.
  2. Calculate the power developed.
  3. If the mass of the box is 10 kg and it moves with a speed of 5 m/s, calculate its kinetic energy.
  4. Name one simple machine that can reduce the effort required to lift this box.
  5. State the principle of conservation of mechanical energy.

End of Worksheet