Science 1C
3.12In Denver, children bring their old jack-o-lanterns to the top of a tower and compete for accuracy in hitting a target on the ground (Figure 3.12). Suppose that the tower is 9.0 m high and that the bull's-eye is a horizontal distance of 3.5 m from the launch point. If the pumpkin is thrown horizontally, what is the launch speed needed to hit the bull's-eye?(2.6m/s)
Fig 3.12 Fig 3.13Fig 3.24
3.13Fairgoers ride a Ferris wheel with a radius of 5.00 m (Figure 3.13). The wheel completes one revolution every 32.0 s. (a) What is the average speed of a rider on this Ferris wheel? (b) If a rider accidentally drops a stuffed animal at the top of the wheel, where does it land relative to the base of the ride? (Note: The bottom of the wheel is 1.75 m above the ground.)(0.982m/s, 1.52m)
3.18A football is kicked with a speed of 9.50 m/s at an angle of 25.0° above the horizontal. If the ball lands at the same level from which it was kicked, how long was it in the air?(0.818s)
3.20Snowballs are thrown with a speed of 13 m/s from a roof 7.0 m above the ground. Snowball A is thrown straight downward; snowball B is thrown in a direction 25° above the horizontal. (a) Is the landing speed of snowball A greater than, less than, or the same as the landing speed of snowball B? Explain. (b) Verify your answer to part (a) by calculating the landing speed of both snowballs.(18m/s, 18m/s)
3.21A golfer gives a ball a maximum initial speed of 30.0 m/s. (a) What is the longest possible hole-in-one for this golfer? Neglect any distance the ball might roll on the green and assume that the tee and the green are at the same level. (b) What is the minimum speed of the ball during this hole-in-one shot?(91.7m, 21.2m/s)
3.24On a hot summer day, a young girl swings on a rope above the local swimming hole (Figure 3.24). When she lets go of the rope her initial velocity is 2.25 m/s at an angle of 35.0° above the horizontal. If she is in flight for 0.616s, how high above the water was she when she let go of the rope?(1.07m)
3.25A certain projectile is launched with an initial speed At its highest point its speed is What was the launch angle? (75.5)
3.26A dolphin jumps with an initial velocity of 12.0 m/s at an angle of 40.0° above the horizontal. The dolphin passes through the centre of a hoop before returning to the water. If the dolphin is moving horizontally when it goes through the hoop, how high above the water is the centre of the hoop? (3.03m)
3.30A football is kicked with an initial speed of 10.2 m/s in a direction 25.0° above the horizontal. Find the magnitude and direction of its velocity (a) 0.250 s and (b) 0.500 s after being kicked. (c) Is the ball at its greatest height before or after 0.500 s? Explain. (9.43m/s, 11.4, 9.26m/s, -3.68)
3.32A golfer tees off on level ground, giving the ball an initial speed of 42.0 m/s and an initial direction of 35.0° above the horizontal. (a) How far from the golfer does the ball land? (b) The next golfer in the group hits a ball with the same initial speed but at an angle above the horizontal that is greater than 45.0°. If the second ball travels the same horizontal distance as the first ball, what was its initial direction of motion? Explain. (169m, 55.0)