Projectile Motion

This week in our lab we learned about projectile motion which is analyzing an object in motion.  An important fact is that the object while in the air is only pushed by  a force of gravity called parabolic trajectory.

   In class we went down to the basketball gym and took videos of us shooting in the baskets with our Vernier Video Physics App.  There we then plotted our points and analyzed our data of the video we took.  From our data we then made graphs to show the direction of the x and y components over time and velocity over time.  In determining the data we found the equation is y=mx+b. Y stands for the acceleration, m is slope also velocity, and x is time.

This is a picture of our x component graphs.  The top picture shows the x component of the object over time.  Change of time over change of position equals slope and also the velocity.  Here we concluded that the slope was constant and same for the velocity.  The bottom graph is x velocity over time which equals acceleration.  Because the slope is 0, there is no acceleration on the x component.

This is a picture of our y component graphs.  The top graph shows the y position over time.  Here the change of time and change of position is not constant which means that it accelerates.  In the bottom graph the y velocity time over velocity crosses over the x axis.  This makes the y values become negative for the x values thus showing it has reached it's top height to which it goes down due to gravity.

Forces in 2D and Circular Motion

1. What does it mean to analyze force in 2D?

   What we think two dimension is flat and pixelated.  To analyze forces in 2D we must measure the x and the y components in a diagonal line.  When we split the x and the y they are defined as two dimensions.  To calculate these two dimensions we use sin, cos, and tangent.  With that we can determine the Fnet for the x and the y.


2. How do forces cause objects to move in a circle?
  In class we had a hover disk attached to a string and circled it around us.  This force we used to pull the hover disk toward us is called centripetal force.  As we are pulling the hover disk there is acceleration, but it is at a constant speed and accelerates through changing directions.

3.  What does it mean to be in orbit?  How do satellites orbit planets?  How do planets orbit the sun?

  To be in orbit means to constantly circling something.  Just like in the hover disk, satellites are pulled through centripetal force circling the planet in gravity.  Planets orbit the sun through a centripetal force of gravity and the satellites orbit the planets.  If the sun was not there scientists say that our planet would go out of orbit and randomly fly off into space.

Impulse Lab

Big Question: What is the relationship between impulse, force, and time during a collision?

• The purpose of this lab was to understand momentum by using the relationship between impulse, force, and time in a collision.  We first pushed a cart with an aluminum loop into another aluminum loop on a force probe.  From there we conducted our data from the computer and measured the velocity of the cart before and after the collision.  With this information we can find the impulse witch is momentum before minus momentum after.  

• Momentum before(f): -.127
• Momentum after(i): .133
• Impulse: .3kg *m/s

Conclusion: We learned that impulse is a change in momentum in this lab.  Force is equal and opposite.  The time increases, the force decreases, and the impulse remains constant in a collision.  

Real World Connection:

   In tennis the players follow through when hitting the ball which is a collision between the racket and the ball.  The act of the serves increase the time which causes a change in momentum witch applies to impulse.  The force depends on how hard the player hits the ball.  By increasing the time on the swing it also increases the velocity which can determine how good your hit is.  

Collisions Lab

Big Questions:
1. What is the difference between the amount of energy lost in an Elastic Collision vs. Inelastic Collision? 2. What is a better conserved quantity - momentum or energy?

In our lab we first set up the two carts, each with a mass of .25kg. After connecting the two range finders to the laptop and matching each one up with the corresponding cart, we began collecting data.

After creating an Elastic Collision, and an Inelastic Collision, we measured the speed of each cart before and after the collision in m/s. Then we calculated the momentum (kg x m/s) and energy (J) of the carts before and after the collisions.

• We then had to collect all our data to get the exact amount of results. 

• This percentage lost in the inelastic collision.

• The percentage lost in the elastic collision.

In our inelastic collision, less energy was lost than in the elastic collision

We also understand that more momentum is conserved than energy because a lot more energy looses sound and friction. 

 

Real World Connections-

 

For a real world connection I think of when i'm playing basketball for collisions.  When I shoot the ball I am aiming for the backboard and the ball collides with it.  There is also momentum because the ball is moving toward at a certain velocity aswell.  When the basktetball collides with the backboard it will continue collide onto the gym floor until it is at rest. 

Rubber Band Cart

• In class we launched a cart from a rubber band and measured the velocity with our electric probes.  We learned that the relationship between energy and velocity is that once the energy of the cart is moving the velocity is double the energy creating kinetic energy. 
• Kinetic Energy (K): the energy in motion. 
• The equation for K is K=1/2 mv squared

• After each run with the rubber band cart we wrote down the velocity of the run and the energy from which we collected last lab. 
• Then we created a line graph with our data.

• Did you know that when your on a roller coaster you are experimenting kinetic energy?  As the rollercoaster is using kinetic energy coming up until it reaches the potential energy on top of a rollercoaster.  Once coming down the rollercoaster you experience more kinetic energy of exhillerating fun. 



 

 

Rubber Band Lab

• The Big Question: How can we store energy to do work for us later?  How does the force it takes to stretch  a rubber band depend on the amount by which you stretch it?
• In the lab we decided to stretch a rubber band in different leghnths and measured our results on how much force we were using. 
• The force F is Fs because that is the force to stretch a rubber band. 
• My table's results were:

1cm=0.01m=0.171N
2cm=0.02m=1.109N
3cm=0.03m=1.659N
4cm=0.04m=2.167N
5cm=0.05m=3.197N

• Here is our data graphed on a line graph.  We then had to find out the Fs of our data which was 95n/mx.  In class we also learned the equation to find the elastic potential energy which is the symbol of Us.  To find the Us we had to find the product of 1/2x times the Fs.  Fs=K times x.
• K=the elastic constant and x= the distance stretched.  Because we cannot use Fs we subtitute it for the K times x making the problem Us=1/2Kxsquared. 

Did you know...



• When using a slingshot there is also elastic potential energy used.  When we pull the object back with the rubber band we are holding energy. It is not until we release the object that we are using the energy from the rubberband. 

MichaelWheatonPhysics

Simple Machines

• In class we learned how simple machines are manipulated by force.  First we made a pully machine and calculated the amount of force it took to lift the weight from 10cm.  We also had to measure the string we had to pull to use the pulley system.  Our goal was to lift a 200g weight with only 0.5 N of force. 
• Had four tries for our experiment.

1. force: 1.5N, string: .13m
2. force: 1.5N, string: .29m
3. force:1.3N, string: .28m
4. force: .53N, string: .28m

• Our next objective was to graph our data.  Since the project was to only graph one bar we had to round our data.  We had two graphs; one with the pulley and one without the pulley system.  Then we put the equation A=(N)(m).  We also learned that half the force is double the distance. 

Did you Know...

• As you move something onto a cart you are using a simple machine.  In what we learned using half the force you can double the distance.  Instead of bringing the object and then lifting it in the truck we are moving on the ramp which is less the force.  In doing so, the ramp also creates double the distance.