Engineering Science – Kinematics
1.4 In Figure 1.4, you walk from the park to your friend’s house, then back to your house. What is your (a) distance traveled, and (b) displacement? (2.65mi, 0.75mi)
Fig 1.4
1.5 A jogger runs on the track shown in Figure 1.5. Neglecting the curvature of the corners, (a) what is the distance traveled and the displacement in running from point A to point B? (b) Find the distance and displacement for a complete circuit of the track. (130m, 100m, 260m, 0m)
Fig 1.5
1.6 A child rides a pony on a circular track whose radius is 4.5 m. (a) Find the distance traveled and the displacement after the child has gone halfway around the track. (b) Does the distance traveled increase, decrease, or stay the same when the child completes one circuit of the track? Explain. (c) Does the displacement increase, decrease, or stay the same when the child completes one circuit of the track? Explain. (d) Find the distance and displacement after a complete circuit of the track. (14m, 9.0m, 28m)
1.7 Kangaroos have been clocked at speeds of 65 km/h. (a) How far can a kangaroo hop in 3.2 minutes at this speed? (b) How long will it take a kangaroo to hop 0.25 km at this speed? (3.5km, 14s)
1.8 Radio waves travel at the speed of light, approximately 186,000 miles per second. How long does it take for a radio message to travel from the Earth to the Moon and back? (The distance to the Moon is 2.39×105 miles.) (2.57s)
1.9 It was a dark and stormy night, when suddenly you saw a flash of lightning. Three-and-a-half seconds later you heard the thunder. Given that the speed of sound in air is about 340 m/s, how far away was the lightning bolt? (1.2km)
1.10 The human nervous system can propagate nerve impulses at about Estimate the time it takes for a nerve impulse generated when your finger touches a hot object to travel to your brain. (0.01s)
1.11 A finch rides on the back of a Galapagos tortoise, which walks at the stately pace of 0.060 m/s. After 1.2 minutes the finch tires of the tortoise’s slow pace, and takes flight in the same direction for another 1.2 minutes at 12 m/s. What was the average speed of the finch for this 2.4-minute interval? (6.0m/s)
1.12 You jog at 9.5 km/h for 8.0 km, then you jump into a car and drive an additional 16 km. With what average speed must you drive your car if your average speed for the entire 24 km is to be 22 km/h? (50 kph)
1.13 You drive in a straight line at 20.0 m/s for 10.0 minutes, then at 30.0 m/s for another 10.0 minutes. (a) Is your average speed 25.0 m/s, more than 25.0 m/s, less than 25.0 m/s? Explain. (b) Verify your answer to part (a) by calculating the average speed. (25.0m/s)