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Fill in the blanks. (i) Work done = _____ multiplied by _____ (in the direction of force).(ii) 1 joule of work is done when a force of _____ newton displaces an object by 1 metre in the direction of the force. (iii) The expression for kinetic energy of a body of mass m and velocity v is _____. (iv) The potential energy of an object of mass m at a small height h from the Earth surface is _____. (v) Power is defined as the _____ at which work is done.
For item one, work equals force multiplied by displacement in the direction of force. For item two, one joule of work occurs when a force of 1 newton moves an object by 1 metre. For item three, kinetic energy equals half m v square. For item four, gravitational potential energy equals m g h. For iteRead more
For item one, work equals force multiplied by displacement in the direction of force. For item two, one joule of work occurs when a force of 1 newton moves an object by 1 metre. For item three, kinetic energy equals half m v square. For item four, gravitational potential energy equals m g h. For item five, power is defined as the rate of doing work.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/
See lessWhen a ball thrown upwards reaches its highest point, tick which of the following statement(s) are correct? (i) The force acting on the ball is zero. (ii) The acceleration of the ball is zero. (iii) Its kinetic energy is zero. (iv) Its potential energy is maximum.
Statements (iii) and (iv) are correct. At the highest point of its vertical flight, the upward velocity of the ball becomes momentarily zero, causing its kinetic energy to drop to zero. Because the height is greatest, its gravitational potential energy reaches maximum. Statements (i) and (ii) are inRead more
Statements (iii) and (iv) are correct. At the highest point of its vertical flight, the upward velocity of the ball becomes momentarily zero, causing its kinetic energy to drop to zero. Because the height is greatest, its gravitational potential energy reaches maximum. Statements (i) and (ii) are incorrect because downward gravitational force and acceleration due to gravity g act continuously on the ball.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/
See lessFor each of the following situations, identify the energy transformation that takes place:(i) a truck moving uphill, (ii) unwinding of a watch spring, (iii) photosynthesis in green leaves, (iv) water flowing from a dam, (v) burning of a matchstick, (vi) explosion of a fire cracker, (vii) speaking into a microphone, (viii) a glowing electric bulb and (ix) a solar panel.
In (i) fuel chemical energy converts to kinetic and potential energy. In (ii) elastic potential energy converts to kinetic energy. In (iii) solar light energy transforms into chemical energy. In (iv) potential energy converts to kinetic energy. In (v) chemical energy converts to thermal and light enRead more
In (i) fuel chemical energy converts to kinetic and potential energy. In (ii) elastic potential energy converts to kinetic energy. In (iii) solar light energy transforms into chemical energy. In (iv) potential energy converts to kinetic energy. In (v) chemical energy converts to thermal and light energy. In (vi) chemical energy converts to sound, light and heat. In (vii) sound energy converts to electrical energy. In (viii) electrical energy converts to light and heat. In (ix) light energy converts to electrical energy.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/
See lessA student is slowly lifted straight up in an elevator from the ground level to the top floor of a building. Later, the same student climbs the staircase, all the way to the top. Given that the height of the building is h = 72.5 m, acceleration due to gravity is g = 10 m s-2 and student’s mass is m = 50 kg. (i) Find the gain in the potential energy if the student is lifted straight up to the top. (ii) Find the gain in the potential energy when the student climbs the stairs to the same top. (iii) What do you conclude about the dependence of the potential energy on the path taken?
In (i), potential energy gain equals m g h, which is 50 kg multiplied by 10 m s-2 multiplied by 72.5 m, yielding 36250 J. In (ii), climbing the stairs reaches the same vertical elevation, giving an identical gain of 36250 J. In (iii), we conclude that gravitational potential energy depends solely onRead more
In (i), potential energy gain equals m g h, which is 50 kg multiplied by 10 m s-2 multiplied by 72.5 m, yielding 36250 J. In (ii), climbing the stairs reaches the same vertical elevation, giving an identical gain of 36250 J. In (iii), we conclude that gravitational potential energy depends solely on initial and final vertical positions, being independent of the path followed.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/
See lessA crane lifts a mass m to the 10th floor of a building in a certain time. It then raises the same mass to the 20th floor of the same building in double the time. How much more energy and power are required? Assume that the height of all floors is equal.
Reaching the 20th floor doubles the vertical displacement compared to the 10th floor, so the required energy m g h doubles, requiring one hundred percent more energy. Power is work divided by time. Because both work and time double simultaneously, the ratio of work to time remains constant. ThereforRead more
Reaching the 20th floor doubles the vertical displacement compared to the 10th floor, so the required energy m g h doubles, requiring one hundred percent more energy. Power is work divided by time. Because both work and time double simultaneously, the ratio of work to time remains constant. Therefore, no additional power is required and the power required remains the same.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/
See less