PHY109-144
XXXXXXXXXXQUIZ 1 XXXXXXXXXXDue: 03/20/2021
Newton’s laws
1) Using Newton’s Gravitational law (F = ) fill in the missing values (----)in the table below
F1 : Gravitational force between m1 and m2 when they are separated by a distance d1
F2 : Gravitational force between m1 and m2 when they are separated by a distance d2
d1 = d2
----F1= F2
d1 = 2d2
---F1= F2
d1 = ---d2
F1= 9F2
d1 = 5 d2
----F1= F2
d1 = ---d2
F1 = 2F2
2) Using Newton’s second law of motion ( ) fill in the missing values XXXXXXXXXXin the table below
Assume F1 = F2 = F constant force applied to both m1 and m2
a1: Acceleration associated with m1
a2 : Acceleration associated with m2
m1 = m2
----a1= a2
m1 = 2 m2
----a1=a2
3m1 = 2m2
----a1= ---- a2
----m1 = ---m2
5a1= 7 a2
-----m1 = ----m2
2a1 = 9 a2
3). According to Newton’s Law of Gravitation, if the distance between two bodies is doubled,
the attractive force between them becomes
( )
twice as large.
Show reasoning:
( )
half as large.
( )
four times as large.
( )
one quarter as large.
( )
unchanged.
4). A hiker covers in the first hour of his hike 6 km, in the second hour 9 km and in the third hour 7 km.
What was his average speed during the hike?
( )
6.0 km/hr.
Show calculation:
( )
7.0 km/h
( )
7.3 km/h
( )
9.5 km/hr.
5). Explain the difference between speed and velocity: (1-2 sentences)
6). A quantity that is a measure of how the velocity of a body changes with time is:
( )
Displacement.
( )
Speed.
( )
Acceleration.
( )
Momentum.
7). A race car
akes and reduces its speed from 300 m/s to 140 m/s in a time of 8 seconds.
Calculate its acceleration (note the sign of a):
Show calculation:
8) A car races around a circular track at the constant speed of 100 m/s (about 225 mph).
The radius of the track is 400 m. The acceleration of the race car is
( )
25 m/s2, toward the center of the track
Show calculation:
( )
50 m/s2, toward the center of the track
( )
50 m/s2, in the direction of travel
( )
100 m/s, in the direction of travel
9). What is the magnitude of the force required to produce this centripetal acceleration,
if the mass of the car is 1500 kg ?(refer to question 3)
( )
25 N
Show calculation:
( )
1500 N
( )
3250 N
( )
37500 N
10). Car A travels with speed v around curve number one, which has a radius r. Car B travels with speed 2v
around curve number two, which has a radius 2r. The acceleration will be
( )
zero for both cars.
Show reasoning:
( )
the same for both cars.
( )
greater for car A.
( )
greater for car B.