Your name __________________________
Quiz #1
PHYSICS 101
Sept 19, 2001
1) The plot below shows the position (x) as a function of time (t) for two trains that run on parallel
tracks. Train A is next to train B at t=0 and at t=Tside-by-side.
Train A
Tside-by-side
x
Train B
t
Which of the following statements is/are true? [circle the correct answer(s), 3 pts]
A) At Tside-by-side, both trains have the same velocity.
B) Both trains speed up all the time.
C) After starting, train A accelerates but train B does not.
D) Both trains have the same velocity at some time before Tside-by-side.
E) At Tside-by-side, the trains have covered different distances.
F) None of the above.
2)You throw a ball straight up in the air. At its highest point:
A) The velocity and acceleration are zero.
B) The velocity is nonzero but the acceleration is zero.
C) The acceleration is nonzero but the velocity is zero.
D) The velocity and acceleration are both nonzero.
[circle the correct answer(s), 1 pts]
3) A person standing on a cliff throws one ball straight up and another straight down at the same
initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the
greatest speed is the one initially thrown:
A) Upward
B) Downward
C) Neither, they both hit at the same speed.
[circle the correct answer, 2 pts]
(Problems 1,2 & 3 are based on the work of E. Mazur and colleagues)
(CONTINUED ON OTHER SIDE)
Rewrite and sign the honor pledge: “I pledge my honor that I have not violated the Honor
Code during this examination.”
_________________________________________________________________________
_________________________________________________________________________
Signature _________________________
3) In the diagram below, a 10 cm long weight is dropped so that it passes the upper detector and then
the lower detector. The time to pass each detector is recorded by a timer. For example, it takes 45 ms
to pass the top detector. You may neglect air resistance and the acceleration of the weight through an
individual detector.
light source
detector
start
timer
0.045 s
stop
v
L
x
start
0.011 s
stop
If the separation between the upper and lower detectors is 5.2 m, what time interval will the bottom
detector record when the weight passes through it? (5 pts)
Physics 101 Quiz #1
September 18, 2002
Name
20 Minutes. Box your answers.
1. [2 points] You have borrowed your roommate’s Porsche 911 GT2, and you are
taking it out for a drive on Route 1. The manufacturer claims that this car can go
from 0 to 28 m/s (62 mi/hr) in 4.1 seconds. What is the rate of acceleration? (Assume
constant acceleration.)
(If you can’t solve problem #1, use a = 10 m/s2 in the remaining problems.)
2. [3 points] You are driving along at 25 m/s (49 mi/hr). There is a traffic signal
200 m ahead of you, which turns yellow. From past experience, you know that the
signal will remain yellow for 7 seconds before turning red. You floor the gas pedal,
so that the Porsche accelerates at its maximum rate. How long does it take you to
reach the signal? Do you get there before it turns red?
(If you can’t solve problem #2, assume the answer is exactly 7 seconds in the remaining problems.)
Continued on the other side....
3. [2 points] After passing the signal, you ease up on the gas, so that you continue to
move at constant speed. What is your speed now?
(If you can’t solve problem #3, assume the answer is v = 40 m/s in the remaining problems.)
4. [3 points] Unfortunately, the speed you calculated in problem 3 is greater than
the speed limit on Route 1, and a police car is waiting, at rest, at the traffic signal.
It is a Ford Crown Victoria, capable of accelerating at a rate of 3.4 m/s2 . It starts
chasing you the instant you pass the signal. You are tempted to speed up—after all,
a Porsche can easily outrun a Crown Vic—but your conscience gets the better of you,
so you continue to move along at constant speed. How much time does it take for the
police car to catch up to you?
Rewrite and sign the honor pledge: “I pledge my honor that I have not violated the
Honor Code during this examination.”
Signature
Name__________________
Quiz 1
Physics 101.
September 19, 2003
1. An arrow is shot straight up with a velocity of 25 m/s. You may take the acceleration
of gravity to be 10 m/s2 in this problem.
(a). How high does it go? [2 points]
(b). A second arrow is shot straight up 1.2 seconds later. Both arrows reach their
peak height at the same time. What was the initial speed of the second arrow? [3
points]
2. A mountain lion is stalking a deer. When the mountain lion is 16 m from the deer,
she is moving at 6 m/s and then begins to accelerate at 2 m/s2. The startled deer runs
away with an acceleration of 3 m2/s. How long until the mountain lion catches up
with the deer, and how far has the deer run? [5 points]
Rewrite and sign the honor pledge: “I pledge my honor that I have not violated the
Honor Code during this examination.”
Signature_________________________
Physics 101 Quiz #1
September 17, 2004
Name
20 Minutes. Box your answers.
Problem 1
At a toy cart starts with a velocity of v0 = 1.0 m/s. In the first 3 seconds, the cart
accelerates with constant acceleration a1 = 2.0 m/s2 , and in the following 3 seconds
undergoes zero acceleration.
1. [2 points] Plot the velocity as function of time on the graph below
v(m/s)
10
9
8
7
6
5
4
3
2
1
t(s)
1
2
3
4
5
6
7
8
9
10
2. [2 points] What is the total distance travelled by the cart in the first 3.0 s?
Continued on the other side....
Continued
3. [2 points] What is the total distance travelled 6.0 s after the start?
4. [4 points] Now, after this 6 s has elapsed, the cart undergoes a constant
deceleration until it comes to a complete stop within a distance of 4.0 meters.
How long will that take? On the graph on the previous page, plot the velocity
during this phase.
Rewrite and sign the honor pledge: “I pledge my honor that I have not violated the
Honor Code during this examination.”
Signature
PRINT YOUR NAME:
QUIZ 1
Physics 101, Fall 2005
September 23, 2005
Throughout, please box your answers!
Problem 1. A car traveling at v0 =40 km/hr east comes to rest in 2 seconds after the driver
applies the brakes. Assume that the acceleration is constant while the car slows down and
stops.
x
a. (2 pts) Determine the acceleration of the car (in m/s2 , magnitude and direction).
b. (3 pts) Determine the stopping distance and the average velocity of the car. (If you could
not solve part (a), assume the acceleration is -10 m/s2 .)
QUIZ 1
Physics 101
y
Problem 2. A gondola attached to a hot-air balloon
is tied down to the ground. Assume the initial position
of the gondola is y = 0. When a car with a constant
velocity of -10 km/hr passes by the gondola, the balloon
starts ascending from rest with a constant acceleration
of 5 m/s2 .
θ
x
a. (3 pts) At what time is θ 30◦ ?
b. (2 pts) When θ = 30◦ , someone riding in the gondola releases a ball. At the time of the
release, the velocity of the ball is identical to that of the balloon. Determine the time the
ball takes to hit the ground. (Hint: The ball will travel up first. If you could not solve part
(a), assume the object is released when the gondola is at a height of 10 m.)
Rewrite and sign the pledge: I pledge my honor that I have not violated the Honor Code during
this examination.
Signature