General Physics 1 (95.103) Exam 1 Sept 30th, 2013
NAME:
Section Number:
You must have:
Topics Covered:
Pen (blue or black)
Scientific Calculator
Formula Sheet
Pencil, Eraser, Ruler
Part 1. Concepts
/15
Part 2. Calculations
/15
Part 3. Problem
/15
Total
/45
Measurement (SI units, Uncertainty)
Vectors
Motion at Constant Acceleration
Forces (Newton’s Laws)
Duration: 50 minutes.
Rules:
Write your name and section number on your paper
Work on the exam paper, in the spaces provided.
Use the back of the pages if you need additional room.
No items on the table except for the above.
No Talking
No papers accepted before the 30 minute mark.
Place your paper in the box as you exit the room.
Recommendations to ensure a good grade:
Draw diagrams. Label everything important.
Show your working
Explain what you are doing and why
Work to an appropriate number of significant figures
All numerical answers need UNITS
Do the easiest questions first!
Don’t leave early.
DON’T PANIC
1
Part 1. Concepts
(3 points each)
1. Which statement about vectors and scalars is correct?
a. Force is a scalar, and velocity is a vector
b. Mass and acceleration are both scalar.
c. Velocity and distance are both vectors
d. Displacement and acceleration are both vectors
2. Which statement is correct according to Newton’s Laws of motion?
a.
b.
c.
d.
Any moving object must be experiencing a net force.
Any object will tend to a state of rest unless acted upon by a force.
Stationary objects are not experiencing any forces.
An object moving at constant velocity is experiencing zero net force.
3. When a baseball player hits a home run, which of the following are true? (After
the ball leaves the bat)
a.
b.
c.
d.
At its highest point the ball’s vertical acceleration is zero
At its highest point the ball’s horizontal velocity reaches its maximum.
The ball’s speed is constant throughout its flight
The ball’s vertical acceleration is constant throughout its flight
4. In a football game, two players collide head-on. If the first player is heavier than
the second player what do Newton’s Laws tell you?
a.
b.
c.
d.
The lighter player experiences a larger force
The heavier player experiences a larger force
Both players experience equal but opposite forces
Both players experience equal but opposite accelerations
5. Sitting in your airline seat in a plane cruising at a very high (but constant) speed,
you throw an apple straight up in the air in front of you. What will happen?
a.
b.
c.
d.
It will land back in your hand
It will likely hit you in the face
It will probably land on the person in the seat behind you
It will probably land on the person in the seat in front.
2
Part 2. Calculations
(circle correct choice, show working for partial credit)
5 questions: [3 POINTS EACH]
1. What is the average speed of a bird that flies a distance of 30 km in two hours?
a.
b.
c.
d.
30 m/s
16.7 m/s
8.3 m/s
4.2 m/s
2. You run upstairs at 4.5 m/s. If the stairs are inclined at 65, what is the
horizontal component of your velocity?
a.
b.
c.
d.
1.9 m/s
4.5 m/s
2.5 m/s
4.1 m/s
3. The gravitational acceleration of objects near the Earths surface has the value g
= 9.8 m/s2. What percentage uncertainty is implied by the number of significant
figures in this number? Or equivalently by how much might ‘g’ vary from one
place to another?
a.
b.
c.
d.
e.
10 %
5%
1%
0.01 %
it is not possible to tell from the information given
4. A car travelling at 60 km/h crashes into the back of a stationary truck. By how
much must the car crumple if the driver’s deceleration is not to exceed a lethal
20-g’s (=196 m/s2)?
a.
b.
c.
d.
9.2 m
0.7 m
6.9 cm
1.3 m
5. On the International Space Station, a 90 kg satellite is to be accelerated from
rest to a velocity of 8 m/s by pulling on it with a cable. What force is needed to
accomplish this in one minute?
a. 882 N
b. 90 N
c. 12 N
d. 0 N
3
Part 3. Problem Solving
[15 points]
A diver runs horizontally off a cliff top 30m above the ocean, in an effort to clear a
patch of rocks that stretch 7m from the cliff base.
A. Draw a diagram showing the complete trajectory of the diver. Incorporate all of the
available information into your diagram. Draw and label vectors to indicate the
horizontal and vertical components of the velocity: at the instant she jumps (Vx0, Vy0),
and at impact with the water (Vx, Vy).
[6 points]
B. How long does it take for the diver to reach the water?
[3 points]
C. How fast does she need to run in order to clear the rocks?
[2 points]
D. What is her final velocity as she hits the water?
[2 points]
E. At what angle does she enter the water?
[2 points]
4
Formula and Data Sheet for Exam 1
Kinematic Formulae
v = v0 + at
x = x0 + v0 t + 12 at 2
v 2 = v02 + 2a(x - x0 )
v + v0
v=
2
Data
g = 9.8 m/s2
 = 3.142
2=1.414
3=1.732
Speed of Sound = 343 m/s
Speed of Light =3x108 m/s
Pythagoras Theorem:
H2 = A2 + B2
Trig functions
Sin  =O/H Cos  = A/H Tan  = O/A
5