Download Physics ~ Fall Final Review

Physics ~ Fall Final Review
1-D Motion & graphing: conversions
integer v. interval; scalar/vector
displacement, velocity, acceleration
BIG 3 equations
Interpreting/drawing graphs
Forces
Force diagrams
Newton’s 3 laws
Gravity
Weight
Friction – coefficient of friction, Forces at an angle (SOHCAHTOA)
2-D motion
Projectile motion – launched horizontally/@ an angle (SOHCAHTOA)
Work & Energy
Work, energy, power
Types of energy: 5 forms; potential, kinetic
Conservation of energy problems
Momentum
Definition
Impulse
Conservation of momentum
DISCLAIMER: These problems include some possibilities for the test. Therefore, the answer to the
question, “If I know everything on this sheet, am I guaranteed an A on the final?” is NO. For
comprehensive review, you must study old test and quizzes, homework sets, corresponding sections of the
text and class notes.
1. Define displacement, velocity, acceleration.
2. Describe the difference b/w scalar and vector measurements.
3. Describe the motion of the objects in the following graphs:
v (m/s)
x (m)
D
B
B
A
C
A
C
t (s)
t (s)
4. Draw a displacement/time and velocity/time graph for an object that accelerates
from the origin at a rate of 1 m/s2 for 3 seconds, stops for 4 seconds and returns to
the origin at a constant velocity of 2 m/s.
5. A squirrel falls from a branch that is 2 meters high. How long does it take to hit
the ground?
6. A car slams on its brakes to avoid hitting a boy on a skateboard. In 3.0 seconds
the car slows from 15.0 m/s to 0.0 m/s. What is the car’s average acceleration?
7. Define force, static friction, kinetic friction, acceleration due to gravity, WEIGHT
8. Draw a free body diagram for the following situations: a) a rock on the ground;
b) a thrown ball as it flies through the air; c) a box being pushed on a frictionless
table
9. State Newton’s 3 Laws of motion.
10. A mover pushes a 100.0 kg box along a frictionless floor with a force of 50 N.
What is the acceleration of the box?
11. A boy falls off his skateboard while moving 10 m/s. If the coefficient of kinetic
friction b/w the ground and the wheels is 0.42, how far will the skateboard roll
before stopping?
12. What is the acceleration (magnitude & direction) of the box:
30 N
m = 10.0 kg
20 N
= 35o
40 N
13. A plane moving 200 m/s drops a 5-kg box while flying at an altitude of 700 m.
Neglecting air resistance, how long will it take for the box to fall? How far will it
travel in the x-direction?
14. A ball is thrown off a bridge with a velocity of 12 m/s at an angle of 23o. How far
will it go in the x-direction?
15. A penguin slides down a glacier that is 30 m high into an ice cold pool. Use the
conservation of mechanical energy to determine it velocity when it hits the pool.
16. A 4 kg box moves to the right at 8 m/s and collides with a 7 kg box moving to the
left at 6 m/s. After the collision the boxes stick together. What is the velocity of
the boxes after the collision?
1. displacement – change in position relative to the origin
velocity – change in displacement over time
aka: speed w/ direction
acceleration – change in velocity over time
2. scalar – measurement w/o direction
vector – measurement WITH direction
3. X/T graph:
A – constant positive velocity
B – stopped
C – constant positive velocity
D – positive acceleration
V/T graph:
A – stopped
B – constant positive velocity
C - stopped
4.
x
(m)
V (m/s)
t (s)
t (s)
5. vo = 0 m/s
a = -10 m/s2
y=-2m
t=?
y = vot + ½ at2
-2 = ½ (-10)t2
t = 0.63 s
6. vo = 15.0 m/s
v = 0 m/s
t = 3.0 s
a=?
v = vo + at
0 = 15 + a(3)
a = -5.0 m/s2
7. force – a push or pull on an object
friction – contact force that opposes motion
static friction – acts on stationary objects
kinetic friction – acts on moving objects
acceleration due to gravity – (g) – rate at which falling objects accelerate
g = -9.81 m/s2 (neglecting friction)
weight – force of gravity acting on an object with mass
Fn
8. a)
Fn
b)
c)
Fpush
Fg = w
Fg = w
Fg = w
9. 1st Law – Law of inertia: An object at rest will remain at rest and an object in
motion will remain in constant motion unless acted on by an unbalanced force.
2nd Law – Law of Acceleration: The acceleration of an object is directly
proportional to the force acting on the object and inversely proportional to the
object’s mass. aka – F = m*a
3rd Law – Law of Action/Reaction: for every force there is an equal and opposite
force
10. F = 50 N
m = 100.0 kg
a=?
F = m*a
50 = 100*a
11. vo = 10.0 m/s
v = 0 m/s
k = 0.42
x=?
F = m*a
a = +0.5 m/s2
Fk = m*a
Fk = k*Fn
k*Fn = m*a
Fn = w = m*g
k*m*g = m*a
(0.42)(-10) = a
a = -4.2 m/s2
v2 = vo2 + 2ax
0 = 102 + 2(-4.2) x
x = 12 m
12.
40 N force:
Fx = F cos 
= 40 cos 35
= 33 N
Fy = F sin 
= 40 sin 35
= 23 N
Fx = 33+ (-20) = 13 N
Fy = 30 + (-23) = 7 N
Fnet
Fy
Fnet = sqrt (132 + 72)
Fnet = 14.8 N
 = sin-1 (7/14.8)
 = 28o
F = m*a
14.8 = 10.0*a
a = +1.48 m/s2 @ 28o
Fx
13.
X
y = vot + ½ at2
Y
vo 200
0
a = 0 -10
x= ?
-700
t=
14. vox = v cos 
vox = 12 cos 23
vox = 11 m/s
voy = v sin 
voy = 12 sin 23
voy = 4.7 m/s
15. hi = 30 m
hf = 0 m
-700 = ½ (-10)t2
t = 11.8 s
x = vot + ½ at2
x = 200 (11.8)
x = 2360 m
vy = voy + at
-4.7 = 4.7 + (-10)t
t = 0.94 s
x = voxt + ½ at2
x = 11 (0.94)
x = 10.3 m
vi = 0 m/s
vf = ?
½ mv2i + mghi = ½ mv2f + mghf
m (10) (30) = ½ m v2
300 = ½ v2
16. m1 = 4 kg
m2 = 7 kg
v1i = 8 m/s
v2i = -6 m/s
v = 25 m/s
vf = ?
m1v1i + m2v2i = (m1+m2)vf
(4)(8) + (7)(-6) = (4 + 7)vf
vf = -0.91 m/s