Impulse Lab

Impulse Lab

Purpose: The purpose of this lab was to measure the impulse of an object, which is another way of looking at the change in momentum in terms of change rather than total. We also wanted to determine what the relationship was between impulse, force, and time during a collision.

Procedure:  We took our red cart with an aluminum ring attached to it and crashed it into our force probe, also with an aluminum ring attached to it. This created a collision, which made it possible for us to measure impulse. This data was recorded onto the Graphical Analysis application on the computer.

Data: We calculated the velocity before and after the collision by measuring the  mean of both. 

Then the computer calculated the area of the Force Time Graph

                          

Results: 

• Velocity Before: .551m/s
• Velocity After: -.495m/s
• Area of Force Time Graph: -.3304s*N

• Momentum Before: (.25kg)(.551m/s) = .138J
• Momentum After: (.25kg)(-.495)= -.124J

• IMPULSE= -.262 kgm/s

Data 2: With all of these calculations we are able to measure the percent difference

Percent Difference= 23%

Equation Time!

Analysis:

• In a collision impulse is conserved (it remains constant) 
• Impulse is Equal but Opposite (inversely related)
• If you add more time in a collision, your force will decrease (and vice versa)
• Newton's 3rd Law: For every action, there is an equal and opposite reaction

Real Life Connection:

Airbags: 

• The importance of airbags are so stressed because in a car crash, and airbag can save your life. The airbag relates to impulse, force, and time because it slows down the rate at which you collide with an object and stop. The airbag adds more time to the collision and therefore it decreases the force, because the two are inversely related.

Arms in a collision:

• Something as simple as holding your arms out when you collide into something can make the collision less harmful. When you hold your arms out it acts as a barrier between you and the wall, and also makes it take more time for you to collide into the wall. Because you are increasing your   total time in the collision, you are decreasing the force of your collision.

Collisions Lab

Collisions Lab

Purpose: The purpose of this lab was to better understand the difference between elastic and inelastic collisions, and what affect each had on the vector and scalar quantities, specifically momentum (vector) and kinetic energy (scalar).

Background:                                         Scalar vs. Vector:

Elastic vs. Inelastic

Procedure: We put two carts (red and blue) of equal mass (.25kg) on each side of the track. We also put two range finders on each end of the track to measure each carts velocity. To record our data we plugged the range finders into the force probe and the force probe into the computer. By doing this we were able to easily measure the velocity (on the graph) of both carts before, during, and after the collision took place. First we did an elastic collision and pushed our red cart(with the spring out) to the right towards the blue cart(also with the spring out). After this collision took place both cars continued to move to the right, but the red cart followed the blue cart at a much slower speed. The next collision we did was an inelastic collision, and again we pushed the red cart to the right toward the blue cart. After this collision though the two carts stuck together (because of the velcro) and both continued to move to the right together.

Data: We then measured the velocity, momentum, and kinetic energy both before and after the collisions. Then we added the two(before and after) together to find the totals of all three of these things.

 Then we found the percent difference of both momentum and energy.

Elastic Collision:

                                

Inelastic Collision:

From this we were able to find the momentum is better conserved than energy(smaller percent difference=less energy given off during a collision). Also that more energy is lost in inelastic collisions than in elastic collisions.

Equation Time!

Momentum: 

P=mv

• P=momentum
• m=mass
• v=velocity

Percent Difference:

(Total Before-Total After)/ (Total Before+ Total After/2)(100)

Real Life Connection:

The concept of momentum in collisions relates to the game of pool. You exert a certain amount of force (using the pool stick) on the white ball. The white ball then (if you actually have an accurate shot) hits one of the colored balls. When it collides with colored ball the colored ball bounces off of the white ball and hopefully into the pocket. This is more of an elastic collision because the white ball does not stick to the colored ball, but still moves in that general direction most of the time.