Download Practice problems for exam 1, solutions will be posted 9/24.

Practice problems for
st
1
exam
1)
One car drives 45 m/s east, another car drives
45 m/s north. Do the 2 cars have the same
velocity? Yes or No
2) Cars 1 and 2 leave Johnson City at the same time.
Car 1 drives straight to Nashville. Car 2 drives to
Chattanooga and then to Nashville, but arrives at
Nashville at the same as Car 1.
Do the cars have the same average speed?
a) Yes b) No
Do the cars have the same average velocity?
a) Yes b) No
3) Ball 1 is thrown horizontally from a 2 m ledge
at the same time Ball 2 is dropped from the
ledge. Which ball reaches ground first?
a) Ball 1 b) Ball 2 c) land at same time
4) A driver driving on a circular track notices
that the speedometer stays constant. Is the
car accelerating. a) Yes b) No
5) Circle the object that has the most inertia.
a) train
b) cat
6) A Puma starting from rest can reach 20 m/s
in a 4 second interval. What is the puma’s
acceleration?
a) 4m/s2
b) 5m/s2
c) 9.8m/s2 d) 10m/s2
7) Which quantities are scalars?
a) mass b) force c) speed d) velocity
8) Which speed is higher?
a) 10 km/hr b) 10 m/s
e) time
9) A ball is thrown at an angle.
The x component of velocity is a) constant b) varies
The y component of velocity is a) constant b) varies
10) What force is needed to give a 2 kg mass an
acceleration of 8 m/s2?
a) 4 N
b) 8 N
c) 16 N
d) 32 N
11) Convert 35 kg/m3 to a density in g/cm3.
12)Convert 45 miles per hour to a velocity with
units m/s.
13) A force vector has components Fx = 3 N, and
Fy = 4 N. What is the force’s magnitude?
a) 3 N b) 4 N
c) 5 N
d) 7 N
14) A 5 kg cat sleeps on a window sill, what
normal force is supporting the cat?
a) 5 N b) 9.8 N c) 49 N
15)A bomb is dropped from a stationary
helicopter hovering 250 m above the ground.
a) How much time is the bomb in the air?
b) What is the bomb’s speed when it hits he
ground?
16)A cannonball is fired from ground level with a
velocity of 20 m/s at an angle of 30 degrees
above horizontal.
A) How far will the cannonball travel?
B) How high is the cannonball at its highest
point?
C) What is the cannonball’s speed at the
highest point?
17) A puma jumps horizontally from a 2 meter
high tree limb in hopes to land on a deer
standing 5 meters horizontally away from the
tree. With what velocity must the puma jump
from the limb to reach the deer?
18) A ball is thrown from a 20 meter high
building, with a velocity of 10 m/s at an angle
of 30 degrees above horizontal How far from
the building, will the ball land?
19) A 1500 kg car is driving 30 m/s. The brakes
are applied and the car comes to a stop over a
50 meter distance. What force did the brakes
exert on the car?
20)A box slides down a 30 degree incline with a
constant velocity. What is the coefficient of
kinetic friction?
21) A person want to place a box on a 50 degree
incline. What coefficient of friction is needed
to keep the box from sliding?
22)A person want to drag a 20 kg sled over a flat
field. The person pulls on the rope
horizontally, and the coefficient of kinetic
fiction is 0.6.
a) With what force must the person pull to
keep the sled moving with a constant
velocity?
b) With what force must the person pull to
give the sled an acceleration of 2 m/s2?
23)
The coefficient of static friction between
a 2 kg book and a wall is 0.4. With what
force must a person press the book into
the wall to keep it from falling?
24) Three forces are applied to a 5 kg box as
shown in the picture. What is the box’s
acceleration vector?
y
(10 N, 30o)
x
(5 N, -900)