Pendulum Problems
ACTIVITY 1: Copy and paste the example problem and the steps, so that the steps are in the correct order into a new Word document and upload it to Moodle. Example Problem 1: A hypnotist swings her watch from 20.0cm chain in front of a subject’s eyes. What is the period of the swing of the watch. Thus, we see that the pendulum used by the hypnotist has a period of 0.898s.| Before we can use this formula, however, we must ensure all our variables are in the correct units. The length variable in this formula should be in meters, however our length is in centimeters. Converting centimeters to meters we get:.| We know that a watch swinging back and forth on a chain is a form of a pendulum and that the length of that pendulum is 20.0cm. Also, since we are assuming that the hypnotist is on Earth, we know that the acceleration due to gravity is 9.8m/s2.| Now we are ready to plug into the formula and simplify to get our answer:.| Fortunately, there is a formula specifically for finding the period of a pendulum. We will use the original version of this formula, since it is already solved for T:.| We want to find the period at which a watch swings back and forth on the end of a chain.|

Example Problem 2: A spider swings in the breeze from a silk thread with a period of 0.6s. How long is the spider’s strand of silk? To solve this we use the formula for the period of a pendulum. Since we are trying to find the length, we use the version of this formula that is solved for L:.| We can see that the spider at the end of the strand makes one complete swing, back and forth, every 0.6s.| Plugging in and simplifying, we get:|

Thus, we now know, that the length of the spider’s silk is 0.089m.| We want to know how long a strand of spider’s silk is.|

ACTIVITY 2: Write up an explanation, similar to the ones you unscrambled in activity one, to the problem below using the work for the problem shown below. Do this on your own paper....

...Chapter 5 pg 143
1. Mass 6.00 kg moved by 18.0N. What is its acceleration?
Divide both sides by m
a=18N/6.00kg convert N = 18N * 1kg*m/s^2 = 18kg*m/s^2
a=18kg*m/s^2/ 6.00 kg = 3m/s^2
a=3m/s^2
7. Truck pulls trailer with friction force of 870 N and a coefficient of friction 0.23. What is the trailer’s normal force.
870N=.023(FN) divide by .023
FN=870N/.023
FN=37826.7N
9. mass 13.0 kg dropped from a cliff. Find its weight
Fw=13.0kg * 9.8m/s^2
Fw=127.4kg*m/s^2
Fw=127.4N
13. A force of 175N needed to keep a 640N engine from sliding. What is the coefficient of static friction?
Ff=175N
FN=640N
divide by 640N
µ=175N/640N
µ=.273
15. find acceleration of a forklift mass 1400kg pushed by force 2100N opposed by frictional force of 425N.
Chapter 6 page 163
3. Box pushed with a force 125 N for 2.00 min. What is the impulse?
Impulse=125N*120s
Impulse=15000Ns=15000(kg*m/s^2)(s)
Impusle=15000kg*m/s
7. 15.0g bullet fired. Muzzle velocity 3250m/s from a rifle with mass 4.74kg and barrel length 75.0 cm.
A) How long is bullet in barrel? d/s=t
B) what is the force on the bullet while in the barrel?
C) Find the bullet’s momentum as it leaves barrel.
a) t=75cm/3250m/s 100cm=1m 75cm/1* 1m/100cm= .75m
t=.75m/3250m/s=2.307E-4s
time in barrel is 2.307E-4 seconds
b)
F=48750g*m/s/2.307X10-4s=48.750kg*m/s/2.307X10-4s
F=211313.394kg*m/s2 X 1N/1kg*m/s2=211313.394N
211,313.394N of force on the bullet as it leaves the barrel.
c) p=mv
p=15.0g * 3250m/s...

...
Free Fall
Rachel Shea
Physics 131 Lab, QL
Hasbrouck 210
Sept. 21, 2014
Abstract
This experiment measures the study of motion by observing the force of gravity acting solely upon an object, and also measures reaction time. If an object is in free fall, the only force acting upon it is gravity. The object used in this experiment was a golf ball that provided some acceleration when dropped. A sensor positioned underneath a table recorded the golf ball’s pattern of motion, when dropped. The main objective of performing this experiment is to measure the velocity and position of the ball to eventually find the acceleration of free fall. A computer program called, DataStudio, was used to create a graph of position vs. time and a graph of velocity vs. time. The second part of the experiment involved randomly dropping a ruler and having your partner catch it to determine reaction time.
Questions
1. The parabolic curves open upward instead of downward because of the golf balls movement over time: where it is dropped from, to where it ends up. The ball begins close to the sensor, then drops to the ground, then bounces back up closer to sensor again, therefore the bounces correspond with the bottom curves of the parabola. If the data were collected from the floor then the curve would open downward. But because the sensor graphs the position from the sensor, the curve was upwards.
2.
-4572009207500
The slope of the velocity versus time graph physically...

...accident such as car crash, since the momentum changes instantly, the force becomes extremely great. Impulsive force is produced during the collision and it will cause severe damage to the car, and may also injure the passengers in it. 3 The passengers’ momentum can be stopped by objects in the car such as dashboard, side door, or windshield, however, it will cause serious injuries because the force would be very great. To increase the safety of the driver and the passengers, safety devices such as seatbelts, air bags, crumple zones, and etc. are introduced. Safety devices such as seatbelts, air bags, crumple zones and etc are designed to reduce the forces on the body if there is a collision. These safety devices are mostly made based on the physics principle of force and momentum, which is
This relationship says that if momentum is transferred over a longer period of time, the force involved is less. If the force of a collision can be reduced, then the chances that someone would get hurt in an accident are lower.4 Since momentum cannot be transformed to another form of energy, it is always conserved during any collision. The change in momentum is then a fixed quantity, and to lower the force, changes have to be made in the time of the collision.5 The time required for the car to stop in a collision have to be increased so that the forces that will impact the occupant will be lower, and they will be less likely to be hurt. If the time taken for the change...

...Is gravity always 9.8m/s2??
INTRODUCTION: A simple pendulum consists of a mass m swinging back and forth along a circular arc at the end of a string of negligible mass. A pendulum is a weight suspended from a pivot so that it can swing freely. Gravity is the pull that two bodies of mass exert on one another. There are several simple experiments that will allow you to calculate the acceleration due to gravity of a falling object. A simple pendulum can determine this acceleration. The only variables in this experiment are the length of the pendulum (L) and the period of one full swing of the pendulum (T). In this case the independent variable represents the length of the string and the dependent variable represents the period of one oscillation. The control variable is the mass of the pendulum. In this lab our goal was to see if we can prove if the acceleration due to gravity is 9.8m/s2. The R2 in this lab is closed to 9.8 m/s2 . The formula that we used in this lab is T=2πLg and then we solved for g=L(T2π)2.
HYPOTHESIS: The gravity will be 9.81 m/s2 at sea level due to the acceleration.
PROCEDURE:
Materials: stopwatch, meter stick, support stand, string, mass (200g), rod clamp, protractor.
Safety: Be careful not to drop any of the heavy materials or to hit somebody near you by using them.
1. Set up the support stand on a flat surface.
2. Tie to mass at the end of the string...

...EXPERIMENT 2 Measurement of g: Use of a simple pendulum
OBJECTIVE: To measure the acceleration due to gravity using a simple pendulum.
Textbook reference: pp10-15
INTRODUCTION:
Many things in nature wiggle in a periodic fashion. That is, they vibrate. One such example is a simple pendulum. If we suspend a mass at the end of a piece of string, we have a simple pendulum. Here, the to and fro motion represents a periodic motion used in times past to control the motion of grandfather and cuckoo clocks. Such oscillatory motion is called simple harmonic motion. It was Galileo who first observed that the time a pendulum takes to swing back and forth through small distances depends only on the length of the pendulum The time of this to and fro motion, called the period, does not depend on the mass of the pendulum or on the size of the arc through which it swings. Another factor involved in the period of motion is, the acceleration due to gravity (g), which on the earth is 9.8 m/s2. It follows then that a long pendulum has a greater period than a shorter pendulum.
Before coming to lab, you should visit the following web site: http://www.myphysicslab.com/pendulum1.html This simulation shows a simple pendulum operating under gravity. For small oscillations the pendulum is linear, but it is non-linear for larger...

...Report : Experiment One
Title: Determination of the acceleration due to gravity with a simple pendulum
Introduction and Theory: A simple pendulum performs simple harmonic motion, i.e. its periodic motion is defined by an acceleration that is proportional to its displacement and directed towards the centre of motion. It can be shown that the period T of the swinging pendulum is proportional to the square root of the length l of thependulum: T2= (4π2l)/g
with T the period in seconds, l the length in meters and g the gravitational acceleration in m/s2. Our raw
data should give us a square-root relationship between the period and the length. Furthermore, to find an accurate value for ‘g’, we will also graph T2 versus the length of the pendulum. This way, we will be
able to obtain a straight-line graph, with a gradient equal to 4π2g–1.
Procedure: Refer to lab manual.
Measurement / Data:
Length of Pendulum ( l +/- 0.1 cm) | Time for 20 Oscillations (s) | Time for 1 Oscillation (Periodic Time) T (s) | T^2 ( s^2) |
| 1 | 2 | Mean | | |
35 | 24.00 | 23.87 | 23.94 | 1.20 | 1.43 |
45 | 26.50 | 26.75 | 26.63 | 1.33 | 1.77 |
55 | 29.94 | 29.81 | 29.88 | 1.49 | 2.23 |
65 | 32.44 | 32.31 | 32.38 | 1.62 | 2.62 |
75 | 35.06 | 35.00 | 35.03 | 1.75 | 3.07 |
85 | 37.06 | 36.87 | 36.97 | 1.85 | 3.42 |
95 | 39.25 | 39.19 | 39.22 | 1.96 | 3.85 |
Length of...

...Using a Pendulum to Determine g
Aim: To determine the rate of acceleration due to gravity using the motion of a pendulum.
Hypothesis: The numerical g value measured on earth is estimated to be 9.8 ms-2
Apparatus:
* Retort Stand
* Boss head and clamp
* Approximately 1 metre of string
* 50g mass carrier or pendulum bob
* Stopwatch
* Metre ruler
Theory:
When a simple pendulum swings with a small angle, the mass on the end performs a good approximation of the back-and-forth motion called simple harmonic motion. The period of the pendulum, that is, the time taken to complete a single full back back-and-forth swing, depends upon just two variables: the length of the string and the rate of acceleration due to gravity. The formula for the period is:
T=2πlg
Where
T = period of the pendulum (s)
l = length of the pendulum (m)
g = rate of acceleration due to gravity (ms-2)
Method:
1. Set up the retort stand and clamp on the edge of a desk as shown in figure 1.7. Tie on the string and adjust its length to about 90cm before attaching the 50g mass carrier or pendulum bob to its end.
2. Using the metre ruler, carefully measure the length of the pendulum from the knot at its top to the base of the mass carrier. Enter this length in your results table.
3. Set the pendulum swimming...

...
Pendulum
Raiyan Hassan
SPH3U
September 20, 2011
Introduction
A pendulum is a device which consists of a mass attached to a string from a frictionless pivot which allows it to swing back and forth. In this experiment, the time it takes for a pendulum to go through a period is going to be measured. The time it takes for a pendulum to go through one period can depend on factors such as the length of the string, mass, or the degree in which the pendulum is released from (amplitude). In this experiment, only different masses will be used in order to prove that mass does not have an effect on the time it takes for a pendulum to go through a period.
Purpose
The purpose of this experiment is to determine the effect of mass on the period of a pendulum.
Hypothesis
If the mass of the pendulum increases then the time for the swing will neither increase nor decrease because the mass does not have an effect on the period of a pendulum.
Materials and Methods
The materials used in this experiment are:
3 Different Masses (20g, 50g, 100g)
Clamp
String
Clock
Protractor
With these materials, the experiment was conducted in the following procedure:
1) Place the clamp to a flat surface with a string attached to it
2) Attach a 20g mass to the end of the string opposite from the pivot
3) Pull the mass to the side with an amplitude of 70º
4)...