What Is the Spring Stiffness Constant in This Car Collision Scenario?

AI Thread Summary
A 1200 kg car traveling at 65 km/h compresses a coiled spring over a distance of 2.2 meters, leading to a calculation of the spring stiffness constant. Using energy conservation principles, the calculated spring constant is approximately 80867 N/m. Initial doubts about the large value were expressed, but upon reevaluation, the answer was confirmed as correct. The significant energy from the car's speed and the short stopping distance contribute to the high stiffness constant. Overall, the calculations align with the physics of the scenario.
skittlez411
Messages
15
Reaction score
0

Homework Statement



A 1200 kg car rolling on a horizontal surface has speed v=65km/h when it strikes a horizontal coiled spring and is brought to rest in a distance of 2.2m. what is the spring stiffness constant of the spring?

Homework Equations



K(final)+Us(final)=K(initial)+Us(initial)
1/2mv^2 + 1/2k(delta x)^2= 1/2mv^2 + 1/2k(delta x)^2


The Attempt at a Solution



1/2(1200)(0) + 1/2k(2.2)^2 = 1/2(1200)(18.06) + 1/2k(0)^2
k = 80867.00826 N/m :bugeye:

The answer looks so big that it doesn't make sense to me. I converted the 65km/h to m/s.

thanks,
nicole!
 
Physics news on Phys.org
Well I didn't check it yet, but think of how much energy a car moving at 65 km/h has! 2.2 meters is quite a small distance for a car to come to a stop!

EDIT: Answer looks OK to me.
 
Last edited:
must be correct
btw...its 18.06^2
i think u hav used it in calculations but missed it here
 
yahh i missed it here. i just double-checked my answer.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top