Since the speed of the bob is constant this is a

Since the speed of the bob is constant, this is a relatively simple kinematics problem. You know the speed, which
you found in the previous part, and you can calculate the distance traveled in one revolution (i.e., the
\texttip{r}{r} = L {\sin}\left({\theta}\right)
\texttip{a}{a} = \large{\frac{v^{2}}{L {\sin}\left({\theta}\right)}}
\texttip{F_{\rm r}}{F_r} = m g {\tan}\left({\theta}\right)
\texttip{v}{v} = \large{\frac{L {\sin}\left({\theta}\right)}{\sqrt{\frac{L {\cos}\left({\theta}\right)}{g}}}}

2/21/16, 10 : 31 AM Homework 4: Applying Newton's Laws
circumference of the circle). From these two you can calculate the time required to travel that distance.
ANSWER:
Correct
Video Tutor: Ball Fired Upward from Moving Cart
First, launch the video below. You will be asked to use your knowledge of physics to predict the outcome of an experiment.
Then, close the video window and answer the questions at right. You can watch the video again at any point.
Part A
The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew
drop the crate? Ignore air resistance.
Hint 1. How to approach the problem
While the crate is on the plane, it shares the plane's velocity. What is the crate's velocity immediately after it is
released?
Hint 2. What affects the motion of the crate?
\large{\frac{2{\pi}L {\sin}\left({\theta}\right)}{\sqrt{gL {\tan}\left({\theta}\right){\sin}\left({\theta}\right)}}}
Page 34 of 44
ANSWER:

2/21/16, 10 : 31 AM Homework 4: Applying Newton's Laws
Page 35 of 44
Correct
At the moment it is released, the crate shares the plane's horizontal velocity. In the absence of air resistance, the
crate would remain directly below the plane as it fell.
Enhanced EOC: Exercise 5.39
A large crate with mass m rests on a horizontal floor. The static and kinetic coefficients of friction between the crate and the
floor are \mu _{\rm{s}} and \mu _{\rm{k}} , respectively. A woman pushes downward on the crate at an angle \theta below the
horizontal with a force \vec F
You may want to review ( page ) .
For help with math skills, you may want to review:
Vector Components
Limits Involving Infinity
For general problem-solving tips and strategies for this topic, you may want to view a Video Tutor Solution of Minimizing
kinetic friction .
.