Download Semester Exam Review

Fall Semester Exam Review- Physics I KEY
Unit 1
Use for questions 1 and 2
a. micrometer
b. meter
c. centimeter
d. megameter
e. kilometer
f. millimeter
1.
The most appropriate SI unit for measuring the length of a book is _c_.
2.
The most appropriate SI unit for measuring the length of the 400 hallway is _b_.
3.
_instrument _ error is when there is a problem with the measurement tool.
4.
_method_ error is when 2 or more different ways are used to measure the same thing with differing
results.
5.
How many significant figures are in 0.05640 ?
6.
How many significant figures are in 13,400 ?
7.
In science the Greek letter delta Δ represents or means Difference or change
8.
3 of the fundamental units in the SI are __meter_ for length, kilogram for mass, and _second___ for
time.
9.
If 3 partners in a lab group all measured a desk and got nearly the exact same answer, their answers are
__precise____.
4
3
10. Convert 9 days to seconds. 9 days x 24 hrs x 60 min x 60 sec = 777,600 sec
11. Convert 4 years to minutes. 4 yrs x 365 days x 24 hrs x 60 min =
Unit 2
1.
What is acceleration? the rate of change of velocity
2.
Fred runs 40 m in 23 s. What is his average velocity? 40 m / 23 s = 1.7 m/s
3.
If an object has a positive velocity and a negative acceleration, describe the motion of the object. moving
forward but slowing down
4.
A car is traveling at 23 m/s. The driver speeds up with an acceleration of 4.5 m/s2. What is the speed of
the car 9.0 seconds later? Vf = 23 m/s + (4.5 m/s2)(9 sec) = 63.5 m/s
5.
Sam accelerates his truck from 10 m/s to 25 m/s in 11.0 s. What is the acceleration of Sam’s truck? a =
(25 m/s - 10 m/s) / 11 s
= 1.4 m/s2
6.
Anna drops a watermelon from the top of a tower. The melon takes 4.5 s to hit the ground. How tall is
the tower? y = ½(9.81)(4.5 s)2 = 99 m
7.
A bus drives for 7.5 hours at an average velocity of 60.0 km/hr. How far has it driven? x = 7.5 hr x 60
km/hr = 450 km
8.
If a piece of paper and a hammer where released at the same time in a vacuum room (no air), what would
be the results?
a. the paper lands first
b. the hammer lands first
c. they land at the same time
d. they don't fall because of the vacuum room
9.
A plane lands with a speed of 90.0 m/s and slows down at an acceleration rate of -5.2 m/s2. How long (in
seconds) will it take for the plane to completely stop?
vf = vi + at therefore t = (vf-vi) / a
t = (0 m/s – 90 m/s) / -5.2 m/s2
t = 17 s
Position (m)
Velocity (m/s)
FIGURE 1
FIGURE 2
Time (s)
Time (s)
10. For the object whose motion is graphed in figure 1, which of the following is true.
a. it is moving at a constant speed
b. it is speeding up
c. it is slowing down
d. it is not moving
e. it is accelerating
11. For the object whose motion is graphed in figure 2, which of the following is true.
a. it is moving at a constant speed
b. it is speeding up
c. it is slowing down
d. it is not moving
e. it is accelerating
12. Which of the following describes an object that is speeding up.
a. it has positive velocity and negative acceleration
b. it has positive velocity and positive acceleration
c. it has negative velocity and positive acceleration
d. it has no velocity and no acceleration
Unit 3
1. Indicate whether each of the following exhibits parabolic motion.
a. Shooting a basketball yes
b. Jumping off a bridge maybe…if you jump upwards first
c. A skier skiing down a hill no
d. A bullet shot from a gun at an upward angle yes
e. A person diving in to a pool from a diving board yes
2.
A ball rolls off the end of a desk traveling at a velocity of 2.5 m/s. If the height of the table is 3.7 m (it’s a tall
table!), how far from the edge of the table does the ball land?
first calculate the time it takes to drop using the formula for vertical displacement
y = ½ gt2
t
2y
t = 0.87 s.
g
then calculate x using the formula for horizontal displacement
x = vxt
x = (2.5 m/s)( 0.87 s)
= 2.2 m
3. What is a vector? a physical quantity that contains both a magnitude and a direction
4. What is a scalar? a physical quantity that contains only a magnitude
5. Identify the following as vector or scalar.
a. velocity vector
b. temperature scalar
c. volume scalar
d. mass scalar
6.
What is a frame of reference? a coordinate system for specifying the location of objects in space
7. Multiplying or dividing vectors by scalars always results in ___vectors___.
8. If you create a graph of an object being thrown into the air, what would each axis represent?
y axis (height) perpendicular to the ground, x axis (distance) parallel to the ground
9. Identify the following as scalar or vector.
a. The number of leaves on a tree scalar
b. wind velocity vector
c. The weight of a person on a scale vector
10. Susie walks 15.0 m east then 12.3 m north. What are the magnitude and direction of her displacement with
respect to her original position?
a2+b2 = c2 therefore c = square root of a2+b2 distance = 19.4 m
to find direction use tangent. tan  = opp/adj
 = tan-1 opp/adj = 39 degrees N of E
11. The path of a projectile is a curved line called a _parabola___.
12. A car drives 40 m west then 115 m south. What is the total displacement and direction of the car?
same method as shown in question #10.
Displacement = 122 m at 19 degrees S of W
use
Unit 4
1. What is a contact force? force that result from physical contact between objects
2. What is a field force? force that do not involve physical contact such as magnetism and gravity
3. What is inertia? The tendency of an object not to accelerate. Inertia means that objects at rest tend to stay
at rest and objects in motion tend to stay in motion.
4. Describe the motion of a car that has a net force acting on it. it will accelerate
5. Draw a free body diagram of a car driving along a road if the forces acting on the car are as follows:
a. weight (gravity) = 21, 500 N
b. normal force = 18, 900 N
c. friction = 7216 N
see example on pp 127-128
6. A man is walking his (stubborn) dog on a leash. To get the dog to move, he exerts a force of 45.0 N directed at
an angle of 30.0° above the horizontal. What is the horizontal component of the force on the dog? first draw a
force diagram. The horizontal component will be the adjacent side of the triangle so you need to use cosine to
find it.
cos  = x/45
45 cos  = x
x = 39 N
7. What do we call forces that act simultaneously in equal but opposite directions?
action-reaction pairs
8. What is mass? What is weight? mass is a measure of the quantity of matter in an object. Weight is a
measure of the force of gravity acting on the object
9. What is Newton’s first law? The law of inertia. An object at rest remains at rest and an object in motion
continues in motion with a constant velocity
10. What is Newton’s second law? What formula do we use to represent this? Acceleration is directly
proportional to net force and inversely proportional to mass. F = ma
11. What is Newton’s third law? For every action there is an equal and opposite reaction
12. A 32 kg box at moving on a horizontal surface requires 58 N of horizontal force to keep it in motion. What is
the coefficient of kinetic friction between the box and the horizontal surface?
k = 58 N / (32 kg x 9.81) = 0.18
13. What is the weight of a 113.2 kg bear? 113.2 kg x 9.81 = 1110 N
Unit 5
1.
The SI unit for Work is _____Joule______
2.
The SI unit for Energy is ____Joule_________
3.
A force does work on an object only if it has a component that is ___parallel_____ to the direction of
motion.
In questions 4-7, which type of energy is involved?
4. a rubber band _elastic potential energy___
5. a book up on a high shelf _gravitational potential energy__
6. a car driving _kinetic energy____
7. a spring __ elastic potential energy ____
8. How much work is done if a 60 kg box is pushed 12 m with a force of 15 N?
W = Fd
W = 15 N x 12 m
W = 180 N
9. A car is traveling at 40 m/s. The breaks apply a force of 30 N causing the car to stop in 14 m. How much work
was done by the brakes? W = Fd
W = 30 N x 14 m W = 420 N
10. As a penny is falling off of a building, what is happening to its potential energy? It is being converted to
kinetic energy
Use the following information for questions 12-14.
Jimmy pulls on a box with a force of 15.0 N to the left while Fred pulls on the same box with 7.0 N to the right. The
box moves 12 m.
12. How much work has Jimmy done?
W = Fd
W = 15.0 N x 12 m
W = 180 N
13. How much work has Fred done?
W = Fd
W = 7.0 N x -12 m
W = -84 N
14. What is the net Work done on the box? 180 N – 84 N = 96 N
Unit 6
1.
The SI unit for power is the: __Watt______
2.
If one motor is rated at 2.0 hp and another is rated at 4.0 hp, which one is more powerful? _4 hp motor__
Which one can do work faster? _4 hp motor __
3.
What is the average power supplied by a 110.0 kg football player running up a 14.5 m flight of stairs in 25.5
seconds?
P = W/t
W = Fd
therefore P = Fd/t
P = (110.0 kg x 9.81 x14.5m) / 25.5 s
= 614 watts
4.
An electric motor uses 1500 J of electricity to raise a 80 N elevator a distance of 15 m. What is the efficiency
of the elevator?
5.
(80 N x 15 m) / 1500 J x 100% = 80%
What is the mechanical advantage of a splitting wedge that converts a 600 N blow from sledge hammer into
2400 N of force splitting open a log? 2400 N / 600 N = 4
6.
What weight is required on the left side to balance the lever system shown below?
1. 0 m x 75 N / 3.0 m = 25 N
?N
3.0 m
1.0 m
75 N
Unit 7
1.
The imaginary line around which objects rotate is called ___axis of rotation______
2.
As a spaceship travels away from earth towards outer space, what happens to the gravitational force it exerts
on the earth? it decreases
3.
What types of objects experience gravitational attraction? all objects
4.
Objects on the moon weigh 1/6th as much as they would on the earth. This is because, compared to the earth
the moon ___has less mass________.
5.
The mass of the moon is approximately 7.4  1022 kg and it has a radius of about 1.738  106 m. How much
would a 75 kg astronaut weigh when standing on the surface of the moon?
Fg = Gm1m2/r2 Fg = (6.673 x
10-11)(7.4  1022 kg)(75 kg)/(1.738  106 m)2
Fg = 123 N
6.
How much force is required to create a 250 N•m torque using a 0.1 m long wrench?
 = Fd
F = /d
F = 2500 N
7.
Where should you push on a door to open it with the least amount of force? Furthest from the hinges
8.
Define rotational and translational motion Rotational motion is when an object is spinning around an axis.
Translational motion is when an object is moving in a straight line.
9.
What type of motion does a ball have when it is rolling along the ground? both types
10. The measurement of the ability of a force to rotate an object around an axis is called: Torque
11. A roller coaster loaded with passengers has a mass of 5.5  103 kg. If the vehicle is traveling at 28 m/s when it
goes around a corner with a radius of 18 m, what is the force exerted on the vehicle by the track? Fc = mv2/r
Fc = (5.5 x 103)(282) / 18 = 2.4 x 105 N
12. A force of 3.0  102 N Force is applied to the end of a 0.4 m wrench. What is the torque?
 = Fd
 = 3.0 x 102 N x 0.4 m
 = 120 N•m
13. A 1200 kg car moving at 32 m/s enters a corner with a radius of 15 m. What is the centripetal force exerted on
the car’s tires by the road? Fc = (1200)(322)/15 = 8.2 x 104 N
14. The force that maintains circular motion is also called: ___Centripetal Force_______
15. A car is driving around a circular track at a constant speed.
a.
Is moving at a constant velocity? no, velocity is constantly changing as the car changes direction
b.
Is it accelerating? yes, it is constantly accelerating because it is constantly changing direction
c.
Is it experiencing centripetal force? yes, because it is moving in a circle
Unit 8
1.
If a skateboarder is skating at 3 m/s and increases her speed to 6 m/s, what happens to her momentum? it
increases
2.
What type of collision occurs when two objects stick together and move as a single unit after colliding?
perfectly inelastic
3.
A 5 kg object and a 10 kg object are dropped from the top of a 10-story building at the same time and reach
the ground simultaneously. As they reach the ground, describe the difference in the objects:
a. speed their speed is increasing at the same rate
b. acceleration they are both accelerating at 9.81 m/s2
c. velocity their velocity is increasing at the same rate
d. momentum Their momentums will be different because their masses are different.
4.
The impulse experienced by an object is equivalent to the object’s change in change in momentum
5.
Two skaters are facing each other. One skater’s mass is 50 kg and the other skater’s mass is 75 kg. If they
skaters push away from each other, describe the differences in the skater’s velocity and momentum They
will both have the same momentum but the smaller skater will have greater velocity
6.
What type of collision occurs when two objects collide, move separately after colliding, and both momentum
and kinetic energy remain constant. elastic collision
7.
A ball moving at 45 m/s has a momentum of 15 kg•m/s. What is the mass of the ball?
p = mv therefore m = p/v
m = 0.33 kg
8.
A 2400 kg car is moving at 45 m/s. What it it’s momentum?
p = mv p = 2400 kg x 45 m/s p = 108,000 kg•m/s
9.
What is the unit used to measure momentum? kg•m/s
10. Air bags help reduce injuries in automobile accidents using what principle of physics? impulse
11. A 500 N force must be applied for 5 seconds to stop a moving cart. If the time interval over which the force is
applied is increased to 10 seconds, how much force is required to stop the cart? half the force or 250 N