# Could someone help me with a few physics GCSE questions

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#1
The spring constant of the spring is 4200 N/m
Calculate the change in the length of the spring when the toy car hits the wall.

Additional info speed of car is 2.2 m/s and mass of car is 500g. Kinetic energy of the car and spring is about 1.2J

Question 2: Evaluate the students model of the crumple zone. Include ideas about how crumple zones make cars safer in your answer.

Additional info: the model is a wall and a toy car with a spring attached to the front.
0
1 year ago
#2
When the toy car hits the wall, it loses all of it's kinetic energy as it comes to rest. The energy is transferred to the spring.

Use to work out the change in length of spring.
1
#3
(Original post by jamiecjx)
When the toy car hits the wall, it loses all of it's kinetic energy as it comes to rest. The energy is transferred to the spring.

Use to work out the change in length of spring.
I’m still a little confused with what extension would be for the equation 1/2ke^2
0
1 year ago
#4
It's a compressible spring, and e is the compression which you want to calculate. (Extension and compression both = e and are equivalent in that formula)
Equate the energy lost by the car, to the energy gained by the spring resulting from its compression.
0
#5
(Original post by Stonebridge)
It's a compressible spring, and e is the compression which you want to calculate. (Extension and compression both = e and are equivalent in that formula)
Equate the energy lost by the car, to the energy gained by the spring resulting from its compression.
Therefore would the inputs be,
1/2 x 4200 x 1.2^2?
As we use the kinetic energy of the spring and car for e which is 1.2J or would it be something else. Sorry to bother you with questions.
0
1 year ago
#6
Why have you subbed the 1.2J in there?
That is the kinetic energy of the car before collision.
in the formula 1/2 ke2
e is what you want to calculate. It's the compression of the spring.
k is the spring constant
put that whole expression equal to the kinetic energy of the car, which is given as 1.2J in order to find e.
1
#7
(Original post by Stonebridge)
Why have you subbed the 1.2J in there?
That is the kinetic energy of the car before collision.
in the formula 1/2 ke2
e is what you want to calculate. It's the compression of the spring.
k is the spring constant
put that whole expression equal to the kinetic energy of the car, which is given as 1.2J in order to find e.
Thank you for the re-explanation, I finally understand the question and got the answer of 0.024. Thank you for your time.
1
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