*28 In Fig. 4-34, a stone is pro- jected at a cliff of height h with an initial spced of 42.0 m/s dirccted at angle 6= 60.0 above the horizontal. The stone strikes at A, 5.50 s after launching. Find (a) the hcight h of the cliff. (b) the speed of the stone just before impact at A, and (c) the maximum height II reached above the ground. Fig. 4-33 Problem 27. 11 Fig. 4-34 Problem 28.

9- A bowling ball of mass 7.5 kg travelling at 10 m sec-irolls off a horizontal table 1 m high. (Assume the acceleration due to gravity is 10 m sec-2, and the effects of air resistance may be ignored unless otherwise stated.) a Calculate the ball's horizontal velocity just as it strikes the floor. b What is the vertical velocity of the ball as it strikes the floor? c Calculate the velocity of the ball as it reaches the floor. d What time interval has elapsed between the ball leaving the table and striking the floor? e Calculate the horizontal distance travelled by the ball as it falls.

10. Wedge Hammer A B 45° -450 mm Fig. 3.20 Neglecting the small amount by which the hammer rises after passing through the vertical through A and assuring that the hammer does not rebound, find the value of R Fig. 3.20 shows a tilt hammer, hinged at 0, with its head A resting on top of the pile B. The hammer, including the arm OA, has a mass of 25 kg. Its centre of gravity G is 400 mm horizontally from O and its radius of gyration about an axis through G parallel to the axis of the pin O is 75 mm. The pile has a mass of 135 kg. The hammer is raised through 45° to the position shown in dotted lines, and released. On striking the pile, there is no rebound. Find the angular velocity of the hammer immediately before impact and the linear velocity of the pile immediately after impact. Neglect any impulsive resistance offered by the earth into which the pile is being driven. [Ans. 5.8 rad/s, 0.343 m/s]

You have your bicycle upside down while you adjust the chain. The chain is wound around the rear wheels small gear, which has a radius of 4.0 cm. At the pedals, the chain is wound around the large gear, which has a radius of 11.0 cm. The radius of the rear wheel is 35.0 cm. You spin the pedals initially so they finish two revolutions in 1.0 s, starting from rest. Assume constant acceleration. (a) Find the angular acceleration of the rear wheel in rad/s2. (b) Find the magnitude of the total acceleration of a point at the edge of the small gear at the end of 1.5 s (the sum of the radial and tangential accelerations). (c) What is the tangential acceleration for that point during the first second? (d) Calculate the linear acceleration of the chain.