Name
KEY
Date ______________
Hour ______
What is Motion? Working With Examples of Motion
Solve the following problems. Show all your work. Remember to include the correct units.
2 pt. each
1. A student practicing for a track meet, ran 250 m in 30 sec.
a. What was her average speed?
250 m = 8.3 m/sec
30 sec.
b. If on the following day she ran 300 m in 30 sec, by how much did her speed increase?
300 m = 10 m/sec
10
30 sec
-8.3
1.7 m/sec.
2. A car traveled 1025 km from El Paso to Dallas in 13.5 hr. What was its average velocity?
1025 km = 75.9 km/hr.
northeast
13.5 hr
3. How fast was a plane flying in km/hr if it traveled 400 km in 30 min.?
30 Min = .5 hrs
400 km = 800 km/hr.
.5 hrs
4. A student walks 10 blocks to a computer store. (Assume all the blocks are equal length.)
a. What is his average speed if he walks 3 blocks in 2 min?
3 blocks = 1.5 blocks/min.
2 min.
b. How long will it take him to reach the computer store?
10 blocks = 6.6 min.
1.5 blocks/ min
5. If the average speed of a car is 45 km/hr, how far can it travel in 40 min.?
40 min. = .66 hr
45 km/hr x .66 hr = 29.7 km
60 min.
6. The speed of light is 3 x 108 m/sec. How long does it take light to travel the 1490 x 108 m
distance from the sun to the Earth?
1490 x 108 m = 496.6 sec or 8.28 min.
3 x 108 m/s
7. A driver starts his parked car and within 5 sec. reaches a velocity of 54 km/hr as he travels east.
What is his acceleration?
54 km/hr = 10.8 km/hr/sec. east
5 sec.
8. Falling objects drop with an average acceleration of 9.8 m/sec/sec or 9.8 m/sec2. If an object
falls from a tall building, how long will it take before it reaches a speed of 49 m/sec?
49 m/s = 5 sec.
9.8 m/s/s
9. A car traveling north with a velocity of 30 m/sec, slows down to a velocity of 10 m/sec within 10
sec. What is the car’s deceleration?
10 m/sec – 30 m/sec = -20 = -2m/sec/sec north
10 sec
10
10. A steel ball whose mass is 100 g is rolling at a rate of 2.8 m/sec. What is its momentum?
100 g x 2.8 m/sec = 280 g-m/sec.
11. A marble is rolling at a velocity 100 cm/sec with a momentum of 10,000 g-cm/sec. What is its
mass?
10000 = mass x 100 cm/sec = 100 g
100
100
12. An object whose mass is 3 kg is fired from a cannon, giving it a forward momentum of 1050 kgm/sec. What is its velocity?
1050 kg – m/sec = 350 m/sec
3 kg