Physical Science 303
Quiz #4, Oct. 30 2007
Name :
1.
A net force of 2000N is exerted on a compact car with a mass of 1000kg. (10pts)
a.
How large acceleration of the car is produced by this force? (2pts)
F=ma, a=F/a=2000N/1000kg = 2m/s
2
b.
If the 2000N force is exerted for 10s, how long will this car travel? (3pts)
d=1/2 a t
2
= 1/2 2m/s
2
(10s)
2
= 100 m
c.
After the first 10s, what is its magnitude of the velocity? If no more force is
exerted, what happen to this car? Explain with one of the Newton’s Laws (5pts)
a=Δv/Δt = (v
f
– v
i
)/Δt, 2m/s
2
= v
f
/10s, v
f
=2m/s
2
x 10s = 20m/s
2.
Steve can drive his Porsche from 0 to 100 mph in 6.3 seconds. (10pts )
(1 mile = 1.609 km)
a.
What is his acceleration in
SI
units?(3pts)
1 mile = 1609.34, 1hr =3600 s
a=Δv/Δt = 100 mph /6.3 s 100 x 1609.34 m/3600 s /6.3s = 7.096 m/s
2
b.
If the car’s mass is 600 kg, what is the net force acting on the car? (4pts)
(Answer in
SI
unit)
F=ma = 600 kg x 7.096 m/s
2
= 4257.6 N
c.
How far down the track is Steve at the end of 6.3 seconds? (3pts)
(Answer in
SI
unit)
d=1/2 a t
2
= 1/2 7.096 m/s
2
(6.3 s)
2
= 140.82 m
3.
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 Spring '08
 MODI
 Mass, International System of Units, Kilogram, net force, SI unit

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