semester 1 final review

Question 1

1. a book resting on a table is given a brief push parallel to the surface and it slides. what forces are acting on the book immediately after the push?
   a. friction, normal force, and gravity
   b. applied force, friction, normal force, gravity
   c. normal force and gravity
2. if there was no friction, what is the motion
   a. not moving
   b. constant speed
   c. accelerating

Answer 1

a. friction, normal force, and gravity

b. constant speed

Question 2

a horse exerts a 500 N force on a wagon, causing it to get faster. What force does the wagon exert on the horse?
a. less than 500 N
b. more than 500 N
c. 500 N

Answer 2

c. 500 N

Question 3

You are in the back of your friend’s truck when it stops on a hill. You jump out and push the truck with 300 N. the truck slowly starts to roll back down the hill. What force does the truck exert on you?
a. none
b. less than 300 N
c. more than 300 N
d. 300 N

Answer 3

d. 300 N

Question 4

a 5kg box is sliding down a ramp that has an incline of 28 degrees at 13 m/s. find all forces

Answer 4

n = 43.3 N
fg = 49 N
fk = 12 N

Question 5

a 38 kg block is at rest, on a table. there is a rope connected to the box and that rope is part of a pulley system. the rope is angled 27 degrees above the horizontal. the other end of the pulley has a 7 kg mass. find all forces
(diagram 1)

Answer 5

T, fs, fg, fg, n

Question 6

diagram 2 questions:
1. which is moving at a greater speed
2. what does the intersection mean
3. which traveled a greater distance and why?

Answer 6

1. object A because it has a greater change in position at the same time
2. the objects are in the same position
3. A because it has a bigger slope

Question 7

diagram 3 questions:
1. what is the displacement
2. what is the average speed
3. what is the average velocity

Answer 7

1. 6m
2. 2m/s
3. 1.2 m/s

Question 8

diagram 4 question
1. displacement from t=1-3

Answer 8

-16 m

Question 9

diagram 5 question:
describe the motion
a. object 1 accelerates while object 2 is at constant velocity
b. object 1 moves at constant velocity and object 2 has 0 velocity and starts ahead
c. object 1 starts ahead at constant velocity and object 2 is at rest

Answer 9

b

Question 10

john and sam run a race. partway there (t=0), sam is at the position of 45 m in a 100 m race. john is 7 m ahead of sam and he runs at 8.54 m/s. what is sams speed it he ties with john
1. whats johns mathematical model
2. whats sams mathematical model
3. how long will it take to get to the end
4. how fast will sam need to be to ti w/ john

Answer 10

1. p(x) = (8.4m/s)(t) + 52m
2. p(x) = (m/s)(t) + 45
3. 5.6 sec
4. 9.8 m/s

Question 11

diagram 6 questions
1. whens object the fastest
2. whens object the slowest
3. when does object change direction

Answer 11

B, E, E

Question 12

diagram 7 questions
1. who has greater magnitude of acceleration from t=6
2. who has greater velocity from 0-10 sec
3. who has displacement from 6-10 sec

Answer 12

1. s
2. t
3. s

Question 13

on a lazy summer day, 2 students play a game where harold throws a ball down at -15 m/s from 44 m above the ground. at the same time. jason throws a ball up from ground. if the balls meet 30m above jason, what velocity must jason throw the ball with?
1. what is harolds mathematical model
2. jasons mm
3. whats jasons initial velocity
4. whats the velocity of jasons ball when it hits harolds

Answer 13

x - 44 = -15t + (1/2)(-9.8)(t^2)

x - 0 = (vo)t + (1/2)(-9.8)(t^2)

43.6 m/s

36.3

Question 14

using diagram 8
1. describe the motion (slowing, CV, faster) and direction of each region

2. using this graph, what is the displacement from t=8 to t=9

Answer 14

1. slower and (-) direction
   cv and (-) direction
   slower and (-) direction
   faster and (+) direction
2. -5 m

Question 15

using diagram 9
what time does the object turn around

Answer 15

at 5.9 sec

Question 16

a bug hits the windshield. how does the force on the car by the bug compare to the force on the bug by the car
a. same
2. the force on the car is greater
3. the force on the bug is greater

Answer 16

a

Question 17

a car and a bug collide. the deceleration of the bug is _______ than the deceleration of the car
1. larger
2. smaller
2. the same as

Answer 17

a

Question 18

a block is pushed to slide up a ramp. whether the block stays on top or slides back down depends on
a. the coefficient of static friction
b. the coefficient of kinetic friction
3. normal force
4. gravity

Answer 18

a

Question 19

after a cannon is fired into a frictionless outerspace vacuum, the amount of force needed to keep it going is
a. the same as the force of the cannon
b. twice the size of the cannons force
c. no force
d. half the force of the cannon

Answer 19

c

Question 20

the acceleration produced by the total force on an object is
a. directly proportional to the total force
b. inversely proportional to the mass
c. the same direction as the total force
d. all of them

Answer 20

d

Question 21

all normal forces are
a. opposite to gravity
b. the same magnitude as gravity
c. perpendicular to the surface producing it

Answer 21

c

Question 22

1. john is 150 kilograms. if john is on a scale on an elevator that is going up at constant velocity, what does the scale read
   a. 150 kg
   b. less than 150
   c. more than 150
2. the same elevator continues to go up, but slows as it gets to the floor. what value would the scale read
   a. 150 kg
   b. less than 150
   c. more than 150

Answer 22

1. 150 kg
2. less than 150 kg

Question 23

which has zero acceleration in all direction
a. with balanced forces on all sides
b. when the object is in constant velocity
c. both
d. none

Answer 23

c

Question 24

diagram 10: no friction and tension = .5

10. mass increases to 2 kg
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know
11. tension increases to 1 N
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know
12. mass and tension are doubled
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know
13. the .5 N tension is applied at an angle (diagram 11)
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know
14. track is inclined (diagram 12)
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know
15. diagram 13
    a. acceleration increases
    b. acceleration decreases
    c. acceleration is the same
    d. impossible to know

Answer 24

a increases

a decreases

a is the same

a decreases

a decreases

a is the same

Question 25

a 5 kg box moves downhill with an acceleration of 2 m/s2 on a 20 degree incline. what is the coefficient of friction

Answer 25

.147

Question 26

as a highway engineer, your responsible for the design of an exit ramp. the ramp need to allow for cars to safely reach a final speed of 15 m/s by the end of the ramp. if the cars are traveling 32 m/s on the highway and have a breaking acceleration of -2.5 m/s2, how long should the ramp be also draw the xt, vt, and at graphs of the cars

Answer 26

159.8 m check accelerated motion free response pg for graphs

Question 27

a student throws a ball up in the air. catching it 4.5 seconds after. what is the initial velocity draw xt, vt, and at graphs of the ball identify what has a value of 0 when the ball is at the peak

Answer 27

velocity is 0 m/s

Question 28

mack is traveling north at 20 m/s and is 150 m ahead of joe. joe is traveling north at 30 m/s how long does it take for joe to catch up w joe determine the distances traveled by joe and mack when they meet up

Answer 28

1. 15 sec 2. m is 300 j is 450

Question 29

a car accelerated from 12 m/s to 25 m/s in 6 sec. what is the acceleration and how far did they travel

Answer 29

a = 2.17 d= 111 m

Question 30

1. A race car travels at a speed of 95 m/ s. How far does it travel in 12.5 s? Use the appropriate mathematical expression and show how units cancel. 2. At t = 0, a second race car is 40 meters behind the first one from problem #1, traveling at 99 m/ s. At what time does it pass the first car? 3. How far will the first car travel during this time? 4. How far will the second car travel during this time?

Answer 30

1187 . 5 𝑚 = 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 t=10 sec 950 m 990 m

Question 31

A car, initially at rest, accelerates at a constant rate of 4.0 m/s2 for 6 s. How fast will the car be traveling at t = 6 s?

Answer 31

24 m/s

Question 32

A tailback initially running at a velocity of 5.0 m/s becomes very tired and slows down at a uniform rate of 0.25 m/s2. How fast will he be running after going an additional 10 meters?

Answer 32

4.47 m/s

Question 33

The expanding gases in a rifle accelerate a 0.005 kg bullet from rest to a speed of 320 m/ s while it is traveling down the 0.820 m long barrel. Find the force of the gases on the bullet. Assume constant acceleration and no friction.

Answer 33

∑ 𝑭 = ( . 𝟎𝟎𝟓 ) ( 𝟑𝟐𝟎^𝟐 / 𝟐(. 𝟖𝟐 ) )

Question 34

In the movie “Raiders of the Lost Ark”, Indiana Jones is dragged behind a truck at a constant speed, hanging on to the handle of his whip, which is wrapped around an axle of the truck. The whip makes a 25° angle above the horizontal, Indy’s mass is 80 kg, and the tension on the whip is 300 N. what is normal and friction force

Answer 34

n = 657.2 N f = 271.9 N

Question 35

1. A 200 lb lifter stands on a scale, holding a 100 lb barbell. The scale reads 300 lbs. He pumps the barbell up and down. What happens to the reading on the scale as he accelerates the barbell upwards? (>300, <300, =300) Why? (A force diagram may help.) 2. What happens to the reading on the scale as he jerks (accelerates) the barbell back down? Why?

Answer 35

>300 lbs <200 lbs

Question 36

An elevator cable exerts a force of 11,000 Newtons on a 750 kg elevator that contains an 80 kg passenger. what is elevators acceleration

Answer 36

a = 3.45