How much work is required to increase the speed of a 1725-kg car travelling on a

Question

How much work is required to increase the speed of a 1725-kg car travelling on a straight horizontal road, in a straight line from 63.00 miles per hour to 72.00 miles per hour in 5.00 s? What is the average horse power of the engine during this speed increase? A spring (of spring constant 18.5 N/m) in a cork gun is compressed by 7.75 cm from its relaxed position and released, Find the speed of the gun's 3.95-g cork as it passes the relaxed position, If the cork sticks to the spring and stretches 3.00 cm before separation, find the cork's speed at separation. A pitcher throw a 255.5-g baseball with an initial speed of 129.6 km/h. Just before the ball is caught at a level 92.0 cm lower, its speed is 120.6 km/h. Find the work due to air drag on the ball, Find the speed at which the ball is caught if there is no air drag.

Explanation / Answer

Using Work-Energy Theorem:

1/2 mv2 = 1/2 kx2

Here x is the compressed length of 7.75 cm

v = [kx2/m]1/2

= (28.30)1/2

  = 5.3038 m/s

b) v =  [kx2/m]1/2

Here x is the stretched position of 3 cm

v = [4.21518]1/2 = 2.0530 m/s

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