Download survey of physics - Stevenson High School

Physics – Lesson Plan
review for final
Unit 1: MOTION
Topics:
 Definitions and equations for…
position
displacement (distance)
average velocity (average speed)
average acceleration
 Difference between average and instantaneous values.
 Motion Graphs
disp vs. time graph
→ displacement by reading off graph
→ velocity from slope
velocity vs. time graph → displacement by area under curve
→ velocity by reading off graph
→ acceleration from slope
acc vs. time graph
→ velocity by area under curve
→ acceleration by reading off graph
If graph is curvy, draw tangent for slopes
 Strobe Plots
 The homework assignments for this unit are:
mot HW #1 – mot HW #5
Activities:
1. Write definitions and equations for terms listed above. Indicate which terms are vectors.
2. Indicate the appropriate line for each of the following:
______ Car at rest
_______ Car travelling slowly in positive direction
_______ Car travelling quickly in negative direction
_______ Car traveling fast in positive direction
What does the slope of a position-time graph represent?
Show the formula for determining the slope of a position-time graph.
3. Answer the following based on the next graph
During what intervals is the cart moving forward?
During what intervals is the cart at rest?
What is the average velocity of the cart from 0-20 s?
What is the instantaneous velocity at 5 s?
What is the displacement from 10-40 s?
What was the cart's position at 25 s?
How far did the cart travel in the first 15 seconds?
What is the average velocity from 10 to 40s?
Physics – Lesson Plan
review for final
4. A runner runs from the 5 meter mark to the 22 meter mark in 5 seconds. What is her average speed?
5. A runner ran for 5 km/hr for 1.0 hour and 4 km/hr for 0.5 hour. What is his average speed for the entire run?
6. If a runner is running at 3.6 km/hr, how long will it take him to run 5 km?
7. A runner runs 50 m east and 25 m west in 20 s. What is her displacement? distance? speed? velocity?
8. A runner stops from 2.6 m/s in 6 seconds. What is his average acceleration?
9. Describe what is known about displacement, velocity and acceleration of the object for each line shown.
Line
8
Displacement
Velocity
Acceleration
A
B
4
C
D
10 s
10. Answer the following based on the following graph.
What is the average acceleration from 10 to 30 s?
What is the instantaneous acceleration at 10 s? 30 s?
What is the velocity at 30 s?
What is the displacement from 10 to 40 s?
11. Compute the instantaneous acceleration at
t = 2s.
12. Identify the instantaneous acceleration at t = 2s
and at t = 4s. Identify the change in velocity
from 0 to 4 s.
13. Draw a strobe plot for a ball for each of the following circumstances.
a. Rolling on a horizontal surface with an acceleration greater than 0.
b. Rolling on a horizontal surface with an acceleration less than 0.
c. Rolling on a horizontal surface with an acceleration equal to 0.
d. Freefall with initial velocity equal to 0, immediately followed by a bounce (maximum height 1/2 the
original height.)
Physics – Lesson Plan
review for final
Unit 2: 2-D MOTION & FORCES
Topics:
 Kinematic Equations
– the 4 equations
– how to chose the correct equation
– what we know about an object in the air
 Vectors
– definition (vector vs scalar)
– rules for sketching
– finding components of vectors at angles (sine and cosine)
– adding vectors at right angles (inverse tangent and Pythagoras Theorem)
– adding vectors at non-right angles
 1-D relative motion
v AC  v AB  vBC
(above is a vector equation, direction matters)
 2-D relative motion
– river problems
 Newton’s Laws of Motion
– 1st Law
– 2nd Law
FNET  ma
 Projectile Motion
– No air resistance  FNET,X = 0
– use kinematic equations for time in the air
– No air resistance  FNET,Y = Fg =mag
– use average velocity for range
 Frictionless Ramps
– force-vector-diagram
– solve for normal force
– solve for acceleration
 The homework assignments for this unit are:
2-D HW #1 – 2-D HW #14
Activities:
1. A cheetah, originally at rest, accelerates 0.4 m/s2 for 5 seconds. What is its final
velocity?
2.
A cheetah, running at 7.0 m/s, accelerates -1.2 m/s2 for 3 seconds. What is its final
velocity?
3.
A cheetah, running at 8.0 m/s comes to a stop in 3.5 m. What is its acceleration?
Physics – Lesson Plan
review for final
4.
A 5-kg bowling ball is dropped from a height of 15 m (assume no air resistance).
What is its velocity just before it hits the ground?
5.
A 5-kg bowling ball is bowled off a 15 m cliff. Its horizontal velocity when it rolls off the
cliff is 2.5 m/s (assume no air resistance). Draw the path the ball takes and show the
force-vector diagram of the ball midflight. Compute how far from the cliff wall the ball
will land (range).
6.
State Newton's first 2 laws -- and give examples of each.
7.
The blue car is travelling 12 m/s west. The red car is traveling east at 9 m/s on the
same road. What is the relative velocity of the blue car as seen from the red car?
8.
You drive 30 km/hr North for1.5 hours and then turn West and drive 40 km/hr for 0.75
hour. How far away are you from your starting point (as the crow flies) and what
direction?
9.
You want to cross a river that is 200 m wide and has a current that runs 0.6 m/s east.
You point your boat (which can travel at 2 m/s) due north and cross the river. How
long will it take you to cross the river? How far down river will you be when you reach
the other side?
10. The treasure map says to start at the old tree. Face north and take 50 paces. Now
turn to face 30 south of east and take 20 more paces. The treasure should be under
your feet! You want to simplify the directions. Determine the direction and number of
paces you must take to walk in a straight line from the old tree to the treasure.
11. You (at 60 kg) are taking 4 dogs for a walk on an icy sidewalk. The Pekingese is
pulling with a force of 4N to the east. The Rottweiler is pulling with a force of 16N to
the south. The cocker spaniel is pulling with a force of 4 N to the west. The Saint
Bernard is pulling with a force of 11N to the north. Which direction will you go? What
will be your acceleration?
12. The hefty toddler (25 kg) was placed on a frictionless slide (30 angle with the
ground). Draw a force vector diagram of the child on the slide. Solve for the normal
force upon the child. What is the net force acting upon the child? What acceleration
will the child experience. Assuming the child rides 3 m down the slide, what will be his
velocity when he comes to the bottom?
13. A 1200-kg car is accelerating eastward at 1.4 m/s2. What is the net force acting upon
the car?
14. You and a sled (total mass = 80 kg) are sliding down an icy hill (NO friction!!), starting
from rest. The hill has a slope of 65. Show the force-vector diagram of the sled on
the hill. What acceleration will you experience going down the hill?
Physics – Lesson Plan
review for final
Unit 3: DYNAMICS
Topics:
 Categorizing Forces
– contact force or field force
– four fundamental forces
 Newton’s Law of Universal Gravity
Fg 
G m1m2
r2
 Newton’s 3rd Law of Motion
– force-vector-diagrams
 String Force (tension)
– sign problems
 Spring Force FSPR  k x
 Friction Force
– use FF,max = μS FN to see if object is moving
– if object is stationary  FF = FP and acceleration = 0
– if object is moving  FF = μK FN and use 2nd Law to get the acceleration
 The homework assignments for this unit are:
dyn HW #1 – dyn HW #7
Activities:
1.
mearth = 5.98 x 1024 kg
rearth = 6.38 x 106 m
30
msun = 1.99 x 10 kg
rsun = 6.96 x 108 m
23
mmars = 6.4 x 10 kg
rmars = 3.40 x 106 m
radius of Mars's orbit around the sun = 2.27 x 1011 m
An object has a mass of 120 kg on earth. What is the gravitational force acting upon that
object on Earth?
What is the gravitational force acting on that object on Mars?
What is the mass of that object on Mars?
What is the gravitational force between Mars and the Sun?
2.
A sign is hung from 2 cables that are attached to adjacent buildings. Each cable makes a 25
angle with the front of its building. The sign has a mass of 20 kg. What is the tension force on
each cable?
3.
A spring with a spring constant of 14,000 N/m is hanging from the ceiling. A 40 kg mass is
hanging from the spring. Draw a force-vector diagram of the mass hanging from the spring.
How much will the spring be stretched?
What is the force that the spring exerts on the mass?
Physics – Lesson Plan
review for final
4.
A 300 kg crate is sitting on the ground. The crate's static coefficient of friction is 0.64 and its
kinetic coefficient of friction is 0.44. Draw a force-vector diagram. With how much force must
the forklift push to get the crate moving?
What force must be used to keep the crate in motion at constant velocity?
5.
A 32 kg box is on a ramp that makes a 40 angle with the ground. The box's static coefficient
of friction is 0.51 and its kinetic coefficient of friction is 0.38. Draw a force-vector diagram.
What is the normal force on the box?
Will the box move?
What is the friction force on the box?
If the box moves, what is its acceleration?
6.
How do the answers for problem 5 change if the ramp angle is reduced to 20?
Physics – Lesson Plan
review for final
Unit 4: MOMENTUM
Topics:
 Momentum
p  mv
 Newton’s 2nd Law
FNET 
– the way he intended
 Impulse
 m v 
t
FNET t  m v 
 Safety Concerns
– want crashes to take more time
– seatbelts
– airbags
– big objects vs. little objects
 Conservation of Momentum
m1v1  m2v2   Before m1v1  m2v2   After
 Collisions (elastic and inelastic) / Explosions
 The homework assignments for this unit are:
mom HW #1 – mom HW #3
Physics – Lesson Plan
review for final
Answers (Unit 1):
2. C
D
A
B
Answers (Unit 2):
Answers (Unit 3):
1. 2.0 m/s
1.
1176 N
443.13 N
120 kg
1.65x1021 N
2.
108.13 N
3.
0.028 m
392 N
4.
1881.6 N
1293.6 N
5.
240.23 N
will move
91.29 N
3.45 m/s2
6.
294.69 N
Will not move
107.26 N
0 m/s2
2. 3.4 m/s
3. 0-10, 40-55 sec
10-15 sec
2 m/s
6 m/s
-100 m
20 m
60 m
-3.33 m/s
3. -9.14 m/s2
4. -17.1 m/s
5. 4.375 m
7. 21 m/s west
8. 54.08 km @ 56.3° N of W
4. 3.4 m/s
5. 4.67 km/hr
9. 100 sec
60 m east
6. 1.39 hrs
10. 43.6 paces @ 66.6° N of E
7. 25 m east
75 m
3.75 m/s
1.25 m/s east
11. south
0.083 m/s2 south
12. 212 N perpendicular to slide
122.5 N down slide
4.9 m/s2 down slide
5.43 m down slide
8. -0.433 m/s2
9. 40 m
30 m
48 m
10 m
8→0 m/s
0→6 m/s
4.8 m/s
0→2 m/s
10. 1 m/s
2 m/s2, 0 m/s2
40 m/s
1100 m
11. 1 m/s2
12. 1 m/s2
-2 m/s2
1 m/s
-0.8 m/s2
0.6 m/s2
0 m/s2
0.2 m/s2
13. 1680 N eastward
14. 8.875 m/s2