momentum

MOMENTUM

DATA LONGGER

Group Members ID NO

NURUL EZZATI BT ABU HASAN D20101037500

NORAZIRAH BT MOHD ARIF D20101037518

NUR IZYAN BT RAZALI D20101037522

Group A

Have you ever seen this situation?

Crumple Zones

What Is Crumple Zone?

Crumple zones are a design feature of an automobile. They have the primary function of

absorbing the energy from a collision. They are part of the body of a car and are designed to ‘crumple’ under impact, rather than retain their structural integrity and therefore resist the force being applied to them. This means that only this smaller area crumples, keeping

the passenger area intact.

ENGAGE

• How do the crumple zones work?• What is involves in the crumple zones activity

and what is the relationship between them?• What types of material is used to make the

most effective crumple zones?

Figure 1- Pasco attached to cart on a track

Momentum Sensor

Interface

Computer

Trolley

track

Planning and Doing Experiment

EMPOWER Data Logger

EMPOWER

monitor

Pasco SENSOR

Power supply

track

trolley

Planning and Doing Experiment

Figure 1- Pasco attached to cart on a track

Maximum Stopping Acceleration

(m/s )

Time to stop

(s)

Without Crumple Zones >60 0.005

With Crumple Zones Heavy- Duty Aluminium Foil Standard Aluminium Foil

Maximum Stopping

Acceleration

(m/s )

Time to stop

(s)

Maximum Stopping

Acceleration

(m/s )

Time to stop

(s)

1 Foil Cylinder 9.40 0.113 >60 0.728

2 Foil Cylinder 9.47 0.064 6.28 0.120

3 Foil Cylinder 14.44 0.050 7.25 0.092

4 Foil Cylinder 15.26 0.047 7.80 0.070

RESULTS

RESULT

QUESTIONS

1. What is the relationship between the maximum stopping acceleration and the maximum stopping. Force experienced by the cart? What physics principle is the relationship based on?

2. What is the relationship between the maximum stopping acceleration and the time it takes the cart to stop? What physics principle is the relationship based on?

3. What is the relationship between the number of cylinders and the maximum stopping acceleration for the heavy-duty foil? Does this same relationship hold for the standard foil? Explain.

4. Based on your data, which crumple zone was the most effective? Which was the least effective? Explain your reasoning.

ANSWERS TO QUESTIONS

1. The maximum acceleration and force are directly related. As one goes up so does the other. This is Newton’s 2nd Law.

2. The maximum acceleration and time to stop the cart are inversely related. As the maximum acceleration increases, the time to stop the cart decreases. This is based on the impulse-momentum theorem. Given the carts all have the same change in momentum, they all require the same impulse to stop the cart. The cart with the largest average acceleration will stop in the shortest amount of time.

3. Answers will vary. For our data, as the number of cylinders increased, the maximum acceleration increased. This is a result of the increased “stiffness” of the crumple zones. This was not the case for the standard foil where a single cylinder was not able to significantly slow the cart before it impacted the end stop. For two or more cylinders, the results were similar to the heavy-duty foil.

4. Answers will vary. From our data, the best crumple zone was the two cylinder, standard foil crumple zone. This had the smallest maximum stopping acceleration and the longest stopping time. The worse crumple zone was the single cylinder standard foil. The cylinder was completely flattened, allowing the cart to impact the end stop with a force comparable to the collision without a crumple zone.

WHAT IS CRUMPLE ZONE??Crumple zone is designed so that the structure of the

car will give way during collision.

ENHANCE PHASE

• The metal of the car will dent, bend and fold during collision• They help reduce injuries by changing shape and absorbing energy through progressive• It controlled and reduced acceleration of the vehicle. A good crumple zone will mean that a car stops in a longer time and longer distance

How crumple zone work??

Crumples zones involve concept of conservation of momentum and conservation of energy.

The momentum change of the vehicle for a given speed is the same as the change in kinetic energy.

By increasing the time of the collision and the distance which collision occurs, it can reduce the amount of force needed to stop the vehicle.

This also reduce the amount of force that acts on the passengers

what is involves in the crumple zone activity ??

Firstly, crumple zone have high

density polymeric foam which contains more tightly formed molecules to make the foam strong, this is places in

front of the cabin

Secondly, reinforced fibres

and spaced between the high density

polymeric foam and the low

density foam

Thirdly, the foam is caged in mechanical ribs

made from either steel or titanium and have been specifically designed to

crush downwards

under the car

Lastly, the front end of the car is built with steel

or titanium. These metal

piece are reinforced with notched metal inserts which will cause the metal to either

crush

What the material that used in crumple zone??