1. 1. v = 55 km/hr t = s d = ?
d = v t ( car is moving at constant speed)
must convert speed to m/s
conversion factors:
1 km = m
1 hr = 60 min
1 min = 60 s
55 km
1000 m
1 hr
1 min
= m/s hr
1 km
60 min
60 s
d = v t
= ( m/s )( 0.50 s )
d = 7.6 m

2. 2. vi = m/s vf = m/s t = 8.0 s a = ?
vf - vi
a = t
96.0 m/s m/s =
8.0 s
64.0 m/s =
8.0 s
a = 8.0 m/s2

3. 3. vi = 30.0 m/s vf = 0 (brought to a stop)
t = 4.0 s
(a) a = ?
vf - vi
a = t
m/s =
4.0 s
negative sign indicates that the car is slowing down
a = m/s2

4. ( ) ( ) 3. vi = 30.0 m/s vf = 0 (brought to a stop) t = 4.0 s
(b) d = ?
( )
vi + vf t
d = 2
( )
m/s
( 4.0 s ) = 2
d = 60 m

5. 4. vi = a = m/s t = s d = ?
d = vi t + ½ a t2
= 0 ( 24.0 s ) + ½ ( 12.0 m/s2 )( 24.0 s )2
= ½ ( 12.0 m/s2 )( 576 s2 )
d = m

6. 5. vi = 20 m/s a = 3.0 m/s d = 300 m vf = ?
vf2 = vi a d
= ( 20.0 m/s ) (3.0 m/s2 )( 300 m )
= 400 m2/s m2/s2
vf2 = m2/s2
vf = m2/s2
vf = m/s

7. 6. vi = m/s a = m/s2 t = s vf = ?
vf = vi + a t
= ( 45.0 m/s ) + ( m/s2 )( 5.00 s )
= ( 45.0 m/s ) + ( m/s )
vf = m/s

8. 7. vi = a = 5.0 m/s vf = 78 m/s d = ?
vf2 = vi a d
vf2 = a d
vf2 = 2 a d
2 a a
( 78 m/s )2
6084 m2/s2
vf2
d = = =
2 a
2 ( 5.0 m/s2 )
10 m/s2
d = 608 m

9. 8. vi = x 102 m/s a = m/s t = s
(a) vf = ?
vf = vi + a t
= ( 200 m/s ) + ( 23.1 m/s2 )( 20.0 s )
= ( 200 m/s ) + ( 462 m/s )
vf = 662 m/s
(b) speed of sound at 0oC = 331 m/s, so the speed of the
plane is about 2x the speed of sound, or Mach 2