1: A 70 kg man runs up a long flight of stairs in 4 s. vertical height of the stair is 4.5 m. Calculate his power. (P = 7.7 ｘ 10² Watts)

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2: A body of mass 2.0 kg is dropped from a rest position 5m above ground. What is its velocity at height of 3.0 m above the ground ? (v = 6.3 m s⁻¹) 



3: A man pulls a trolley through a distance of 50 m by applying a force of 100N which makes an angle of 30° with horizontal. Calculate the work done by the man. (4330 J)

4: The roller-coaster car starts its journey from a vertical height of 40 m on the first hill and reaches a vertical height of only 25 m on the second hill, where it slows to a momentary stop. It traveled a distance of 400 m. Determine the thermal energy produced and estimate the average friction force on the car whose mas, 1000 kg. (Ans. 147,150 J, 370 N)

5: A man whose mass is 70 kg walks up to the third floor of building which is 12m above the ground in 20s. Find his Power in watts and hp. (P = 411.6 watt = 0.55 hp)

6: To what height can a 400 W engine lift a 100 kg mass in 3s? (h= 1.22 m) 



7: A ball of mass 100 g is thrown vertically upward at a speed of 25 ms⁻¹. If no energy is lost, determine the height it would reach. If the ball only rises to 25m, calculate the work done against air resistance. Also calculate the force of friction. (31.9 m, 6.7 J, 0.3 N)

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8: An object of mass 1000 g falls from a height of 30m on the sand below. If it penetrates 4cm into the sand, what opposing force is exerted on it by the sand? Neglect air friction. (f = 7350 N) 



9: A body of mass 'm' drops from Bridge into water of the river. The bridge is 10m high from the water surface. (a). Find the speed of the body 5m above the water surface. 

(b). Find the speed of the body before it strikes the water. 

((a) 9.9 m s⁻¹ (b) 14 m s⁻¹) 

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10: The engine of a JF-Thunder fighter (made by Pakistan and China) develops a thrust of 3000 N. What horsepower does it at a velocity of 600 m s⁻¹? (2413 hp)  

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11: The mass of the moon is 1/80 of the mass of the earth and corresponding radius is 1/4 of the earth. Calculate the escape velocity on the surface of moon. (2.5 km s⁻¹)

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