Ncert – class 9- science – Chapter 10 – Work and Energy 1 Welcome to your Ncert - class 9- science - Chapter 10 – Work and Energy 1 1. When the force and the displacement are in the opposite directions, the work done by the force is .......... notformthis zero negative positive None 2. 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 6m 8m 10m 4m None 3. 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 -3J -12J -9J -6J None 4. At the start of the free-fall of an object from height ℎ, the potential energy is _____ and kinetic energy is _____. Zero mgh mgh, infinite mgh, zero Infinite, mgh None 5. We can explain free-fall of an object on the basis of? Work-energy theorem Conservation of energy Conservation of Kinetic energy Conservation of potential energy None 6. A ball rolling on the ground possesses no energy heat energy potential energy kinetic energy None 7. 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 ) 10000kg 7,500kg 500kg 5000kg None 8. 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) $$ 40 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 30 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 10 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 20 \mathrm{kJ} / \mathrm{m}^{3} $$ None 9. When a body falls freely towards the earth, then its total energy: Remains constant First increases and then decreases Decreases Increases None 10. Work done is equal to? Acceleration Change in kinetic energy Kinetic energy None of these None 11. Whenever energy gets transformed, the total energy_______. Varies with time Remains unchanged None of these Varies with position None 12. The spring will have maximum potential energy when neither (a) nor (b) it is pulled out both (a) and (b) it is compressed None 13. 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 75 W 300 W 150 W 600 W None 14. 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 15. 9800 joule of energy was spent to raise a mass of 50kg, the mass was raised to a height of 980m 20m none of these 10m None 16. If a body is released from a certain height, during its fall. Its potential energy increases and kinetic energy decreases. Both potential and kinetic energy of the body decrease Its kinetic energy increases and potential energy decreases Both potential and kinetic energy of that body increase None 17. A body is falling a height ℎ. After it has fallen a height ℎ/2. it will possess only potential energy only kinetic energy more kinetic and less potential energy half potential energy and half kinetic energy None 18. 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 $$ t^{2} $$ $$ t^{3/ 2} $$ $$ t^{3/ 4} $$ $$ t^{1 / 2} $$ None 19. 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 0.71K 2K 0.25K 0.5K None 20. 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 20 J 50 J 10 J 15 J 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.
