Physics 213
HW-04 SELECTED SOLUTIONS
TOPIC: PROJECTILE MOTION
Direction of Velocity at Various Times in Flight for Projectile Motion Conceptual Question
For each of the motions described below, determine the algebraic sign (positive, negative, or zero) of
Physics 213 - Fall 2013; 10/09/2013
QUIZ 4 (20p+2p bonus)
Solution
t2
Impulse and Change in Momentum: J Fnet dt Fnet ,av t p p 2 p1
p mv
t1
Work done: by a (single) constant force: W F d Fd cos F d
Kinetic Energy:
1
p2
E kin mv 2
2
2m
Work-Energy Theor
Physics 213 - Fall 2013; 10/23/2013
QUIZ 5 (20p+2p bonus)
Mechanical Energy: E
mech
Solution
E kin E pot
pot
Potential Energy: Gravitational EG
m g h
mech
Work and Mechanical Energy: Ei
Work-Energy Theorem: Wnet E kin
1
E kin mv 2
2
1
2
pot
Elastic: Eel
Physics 213
HW-08 SELECTED SOLUTIONS
Understanding Work Done by a Constant Force
Learning Goal:
To explore the definition of work and learn how to find the work done by a force on an object.
When energy is transferred either to or away from an object by a
Physics 213
HW-09 SELECTED SOLUTIONS
Exercise 6.19
Use the work-energy theorem to solve each of these problems. You can use Newton's laws to check
your answers. Neglect air resistance in all cases.
a) A branch falls from the top of a 95.0-m tall redwood t
Physics 213
HW-10 SELECTED SOLUTIONS
Potential Energy Graphs and Motion
Learning Goal: To be able to interpret potential energy diagrams and predict the corresponding motion of a
particle.
Potential energy diagrams for a particle are useful in predicting
Physics 213
HW-11 SELECTED SOLUTIONS
Topic: Collisions
Colliding Cars
In this problem we will consider the collision of two
cars initially moving at right angles. We assume that
after the collision the cars stick together and travel off
as a single unit.