Ncert – class 9- science – Chapter 10 – Work and Energy 1 Welcome to your Ncert - class 9- science - Chapter 10 – Work and Energy 1 1. Work done is equal to? Kinetic energy Change in kinetic energy Acceleration None of these None 2. Whenever energy gets transformed, the total energy_______. None of these Varies with position Varies with time Remains unchanged None 3. If water is flowing in a pipe at a height 4m from the ground then its potentialenergy per unit volume is (Reference is taken at ground, g=10m/s 2) $$ 40 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 20 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 30 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 10 \mathrm{kJ} / \mathrm{m}^{3} $$ None 4. Is the work required to be done by an external force on an object on a frictionless, horizontal surface to accelerate it from a speed v to a speed 2v. twice the work required to accelerate the object from v=0 to v equal to the work required to accelerate the object from v=0 to v, three times the work required to accelerate the object from v=0 to v, four times the work required to accelerate the object from 0 to v None 5. When a body falls freely towards the earth, then its total energy: Decreases First increases and then decreases Increases Remains constant None 6. A ball of mass 2 kg hits a floor with a speed of 4 m/s at an angle of 60ºwith the normal. If (e=1/2); then the change in the kinetic energy of the ball is -6J -12J -9J -3J None 7. A ball is allowed to fall from a height of 10m. if there is 40% loss of energy due is impact then after one impact ball will go up to 10m 6m 4m 8m None 8. When the force and the displacement are in the opposite directions, the work done by the force is .......... zero notformthis positive negative None 9. A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to $$ t^{3/ 4} $$ $$ t^{3/ 2} $$ $$ t^{2} $$ $$ t^{1 / 2} $$ None 10. At the start of the free-fall of an object from height ℎ, the potential energy is _____ and kinetic energy is _____. mgh, zero mgh, infinite Infinite, mgh Zero mgh None 11. A body is falling a height ℎ. After it has fallen a height ℎ/2. it will possess only kinetic energy half potential energy and half kinetic energy more kinetic and less potential energy only potential energy None 12. 9800 joule of energy was spent to raise a mass of 50kg, the mass was raised to a height of none of these 980m 20m 10m None 13. The height of the water dam in the hydroelectric power station is 20 m. How much water. in 1 second, should fall on turbine, so that 1 MW power is generated ?(g=10m/s^2 ) 7,500kg 500kg 5000kg 10000kg None 14. A constant force of 5N is applied on a block of mass 20 kg for a distance of 2.0 m, the kinetic energy acquired by the block is 50 J 10 J 20 J 15 J None 15. We can explain free-fall of an object on the basis of? Work-energy theorem Conservation of Kinetic energy Conservation of potential energy Conservation of energy None 16. A ball rolling on the ground possesses potential energy no energy kinetic energy heat energy None 17. Bullet 2 has twice the mass of bullet 1. Both are fired so that they have the same speed. If the kinetic energy of bullet 1 is K, is the kinetic energy of bullet 2 2K 0.5K 0.25K 0.71K None 18. If a body is released from a certain height, during its fall. Its potential energy increases and kinetic energy decreases. Its kinetic energy increases and potential energy decreases Both potential and kinetic energy of that body increase Both potential and kinetic energy of the body decrease None 19. From an automatic gun a man fires 360 bullets per minute with a speed of 360 km/hr. If each bullet weighs 20g, the power of the gun is 150 W 300 W 75 W 600 W None 20. The spring will have maximum potential energy when neither (a) nor (b) it is pulled out both (a) and (b) it is compressed None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
