Questions

Note: Neglect all frictional forces in all exercises.

1		A boat moves 15.0 km across a lake in 45 min. (a) What was the average speed in meters per second? (b) What was the average speed in kilometers per hour?
2		If the Sun is a distance of 1.5 x 108 km from Earth, how long does it take sunlight to reach earth if it moves at 3.0 x 108 m/s?
3		How many meters away is a cliff if an echo is heard one-half second after you yell "hello"? Assume that sound traveled at 343 m/s on that day.
4		A car has an average speed of 80.0 km/hr for one hour, then an average speed of 90.0 km/hr for two hours during a three-hour trip. (a) How far did the car travel during the trip? (b) What was the average speed for the trip?
5		What is the acceleration of a car that moves from a speed of 5.0 m/s to a speed of 15 m/s during a time of 6.0 s?
6		How much time is needed for a car to accelerate from 8.0 m/s to a speed of 22 m/s if the acceleration is 3.0 m/s2?
7		What was the initial speed of a car that required 13.7 m to stop in 4.00 s?
8		What is the average speed of a car that travels 270.0 miles in 4.50 hours?
9		A ferryboat requires 45.0 min to travel 15.0 km across a bay. (a) What was the average speed in m/s? (b) At this speed, how much time would be required for the boat to take a 420 km trip up the river?
10		A car with an average speed of 60.0 mi/hr (a) will require how much time to cover 300.0 miles? (b) will travel how far in 8.0 hours?
11		A rocket moves through outer space at 11,000 m/s. At this rate, how much time would be required to travel the distance from Earth to the Moon, which is 380,000 km?
12		Sound travels at 1,140 ft/s in the warm air surrounding a thunderstorm. How far away was the place of discharge if thunder is heard 4.63 s after a lightning flash?
13		How many hours are required for a radio signal from a space probe near the planet Pluto, 6.00 x 109 km away, to reach Earth? Assume that the radio signal travels at the speed of light, 3.00 x 108 m/s.
14		A rifle is fired straight up, and the bullet leaves the rifle with an initial velocity magnitude of 724 m/s. After 5.00 s the velocity is 675 m/s. At what rate is the bullet decelerated?
15		An airplane is accelerated uniformly from rest to 95.0 m/s in 6.33 s. What is the acceleration of the plane?
16		A racing car accelerates from 40.0 m/s to 80.0 m/s in 10.0 s. What is the acceleration?
17		What is the velocity of a car that accelerates from rest at 6.0 m/s2 for 5.0 s?
18		A car with an initial velocity of 30.0 m/s is able to come to a stop over a distance of 100.0 m when the brakes are applied. (a) How much time was required for the stopping process? (b) How many g's did the driver experience?
19		A rock thrown straight up climbs for 2.50 s, then falls to the ground. Neglecting air resistance, with what velocity did the rock strike the ground?
20		An object is observed to fall from a bridge, striking the water below 2.50 s later. (a) With what velocity did it strike the water? (b) What was its average velocity during the fall? (c) How high is the bridge?
21		A ball dropped from a window strikes the ground 2.00 seconds later. How high is the window above the ground?
22		What is the resulting velocity if a car moving at 10.0 m/s accelerates at 4.00 m/s2 for 10.0 s?
23		If a rock in free fall is moving at 96.0 ft/s, how long has it been falling?