2. September 14, 2011
A person initially at point P in the illustration stays there a moment then
moves along the axis to Q and stays there a moment. She then runs quickly
to R, stays there a moment, and then strolls slowly back to P. Which of the
position vs. time graphs below correctly represents this motion?
4. September 27, 2011
A car moves along the x axis. What is the sign of
the car’s acceleration if it is moving in the
positive x direction with
increasing speed?
decreasing speed?
What is the sign of the acceleration if the car
moves in the negative direction with
increasing speed?
decreasing speed?
5. Average Acceleration
A car accelerates along a straight road as
illustrated below. What is the magnitude of its
average acceleration?
+15km/h/s
6. Average Acceleration
An automobile is moving to the east along a
straight highway. Then the driver puts on the
brakes. Using the information from the graphic,
what was the car’s average acceleration during
braking?
2.0m/s2 West
7. Average Acceleration
A car moves to the west as show in the diagram.
What is the car’s average acceleration?
2.0m/s2 East
8. Runway Design
You are designing an airport for small planes. One
kind of airplane that might se this airfield must
reach a speed before takeoff of at least 27.8m/s,
and can accelerate at 2.00m/s2 . What is the
minimum length that the runway must be?
193m
9. Acceleration of a car
How long does it take a car to cross a 30.0m wide
intersection after the light turns green, if the
car accelerates from rest at a constant
2.00m/s2?
5.48s
10. Taking the baby for a jog
A person pushing a jogging stroller at 1.00m/s
starts uniformly accelerating at a rate of
0.500m/s2. What is the velocity of the stroller
after it has traveled 4.75m?
2.40m/s
11. Free Fall
Time (s) Velocity (m/s)
0 0
1 10
2 20
3 30
… …
t 10t
12. Free Fall
What is the speed of a falling rock 3.5s after
being dropped from rest?
34.3m/s down
6s after being dropped?
58.9m/s down
10s?
98.1m/s down
14. Tower Drop
Suppose that a ball is dropped from a tower
70.0m high. How far will the ball have fallen
after 1.00s?
4.90m down
2.00s?
19.6m down
3.00s?
44.1m down
15. Tower Throw Down!
Suppose the ball is instead thrown downward with
an initial velocity of 3.00m/s. How far will it have
fallen after 1.00s?
7.90m down
after 2.00s?
25.6m down
Compare the speed of the dropped ball with the
speed of the thrown ball after 2.00s have passed.
19.6m/s vs. 22.6m/s
16. Eww – Throw Up!
A person throws a ball up into the air with an
initial velocity of 15.0m/s. Calculate (a) how high
it goes and (b) how long it is in the air before it
comes back to his hand.
(a) 11.5m up
(b) 3.06s
Find the time at which the ball in the question
above is 8.00m high? (Quadratic)
0.69s (on the way up) and 2.37s (on the way down)
20. Crosswind Landing
A pilot is flying a plane due south to warmer
weather at 275km/h as a wind carries him due
west at 35km/h. Find the magnitude and
direction of the plane’s resultant velocity.
21. Crosswind Landing
A pilot needs to approach for a landing at
250km/h 30˚ W of S with the presence of wind
blowing due West. What is the velocity of the
wind? What is the velocity with which he must fly
the plane?
24. The Race
Two balls are launched simultaneously from the
same height. Ball A is released from rest, and
drops straight down. Ball B is given an initial
horizontal velocity. Which ball hits the ground
first?
Ball A
Ball B
Both balls hit the ground at the same time
25.
26. The Ballistics Cart
A ballistic cart is a cart that can shoot a ball
vertically and (maybe) catch it again. With the
cart rolling at constant speed when it shoots the
ball, where will the ball land?
In the cart
Behind the cart
Ahead of the cart
27.
28. What do you think?
Consider the situation depicted here. A gun is
accurately aimed at a dangerous criminal hanging
from the gutter of a building. The target is well
within the gun’s range, but the instant the gun is
fired and the bullet moves with a speed of v0 , the
criminal lets go and drops to the ground. What
happens? The bullet
hits the criminal regardless
of the value of v0 .
hits the criminal only if
v0 is large enough.
misses the criminal.
29.
30. October 18, 2011
At which point or points on the graph below is…
Vx = 0m/s
the vertical velocity zero.
the horizontal velocity nonzero.
the vertical acceleration zero.
the horizontal acceleration zero.
the vertical velocity positive.
the vertical acceleration nonzero.
31. Horizontal Launch
∆t ∆x vx vy ∆y
0s 0m 20m/s 0 0m
1s 20m 20m/s -9.8m/s -4.9m
2s 40m 20m/s -19.6m/s -19.6m
3s 60m 20m/s -29.4m/s -44.1m
An object is launched horizontally at 20m/s off a
cliff.
What is its velocity after 1.0s?
Where is it at 1.0s?
If the cliff is 30m tall, how high from the base of the
cliff did the object land?
33. Give it a shot!
A person standing at the edge of a seaside
cliff kicks a stone over the edge with a speed
of 18m/s. The cliff is 52 m above the water’s
surface.
How long does it take for the stone to fall to the
water?
With what speed does it strike the water?
34. October 19, 2011
I am working on the bullet question. We will
discuss it Friday!
A ball rolls off of a 12m tall cliff and lands 14m
from the base. With what velocity was it rolling?
8.97m/s
35. Tricky, tricky!
A spy in a speed boat is being chased down a river
by government officials in a faster craft. Just as
the officials’ boat pulls up next to the spy’s boat,
both boats reach the edge of a 5.0 m waterfall.
If the spy’s speed is 15 m/s and the officials’
speed is 26 m/s, how far apart will the two
vessels be when they land below the waterfall?
36. Oh OH!
Four dozen exotic animals, including lions, tigers,
bears, wolves, cheetahs, and giraffes, are
currently on the loose in Ohio. A zoologist
standing on a cliff spots a monkey hanging from
tree 10.5m tall, 140m away. He takes aim at the
monkey with a tranquilizer gun. The barrel of the
gun is horizontal. If the tranquilizer dart travels
at 70.0m/s. If the monkey lets go of the tree at
the same time the dart is fired, what height
above the ground will the monkey be at when he is
hit by the dart?
37. Launch at an Angle
A human cannonball is launched at 20m/s at 35˚
above horizontal. Assume ground-to-ground
trajectory. Neglecting air resistance…
Find the maximum height that
he reaches.
How long is he in the air?
How far from the cannon
does he land?
What is his velocity at 1.0s?
What is his minimum velocity?
What is his velocity when he
lands?
