Ncert – class 9- science – Chapter 10 – Work and Energy 1 Welcome to your Ncert - class 9- science - Chapter 10 – Work and Energy 1 1. 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 10000kg 5000kg None 2. At the start of the free-fall of an object from height ℎ, the potential energy is _____ and kinetic energy is _____. mgh, zero Zero mgh mgh, infinite Infinite, mgh None 3. 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 75 W 300 W 600 W None 4. If a body is released from a certain height, during its fall. Both potential and kinetic energy of the body decrease Both potential and kinetic energy of that body increase Its potential energy increases and kinetic energy decreases. Its kinetic energy increases and potential energy decreases None 5. When a body falls freely towards the earth, then its total energy: Increases Decreases Remains constant First increases and then decreases None 6. A body is falling a height ℎ. After it has fallen a height ℎ/2. it will possess half potential energy and half kinetic energy more kinetic and less potential energy only kinetic energy only potential energy None 7. 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 $$ t^{2} $$ $$ t^{1 / 2} $$ $$ t^{3/ 4} $$ $$ t^{3/ 2} $$ None 8. 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 9. When the force and the displacement are in the opposite directions, the work done by the force is .......... positive zero notformthis negative None 10. 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 -3J -12J -9J None 11. 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 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 equal to the work required to accelerate the object from v=0 to v, None 12. 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 0.25K 0.71K 0.5K None 13. Work done is equal to? Acceleration Kinetic energy Change in kinetic energy None of these None 14. 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 15. Whenever energy gets transformed, the total energy_______. None of these Varies with position Remains unchanged Varies with time None 16. The spring will have maximum potential energy when neither (a) nor (b) both (a) and (b) it is pulled out it is compressed None 17. 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) $$ 10 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 20 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 30 \mathrm{kJ} / \mathrm{m}^{3} $$ $$ 40 \mathrm{kJ} / \mathrm{m}^{3} $$ None 18. A ball rolling on the ground possesses no energy potential energy heat energy kinetic energy None 19. 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 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 50 J 15 J 10 J 20 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.
