##### An automobile having a mass of 1,000 kg is driven into a brick wall in a safety

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An automobile having a mass of 1,000 kg is driven into a brick wall in a safety test. The bumper behaves like a spring with constant 4.40 ✕ 106 N/m and is compressed 2.95 cm as the car is brought to rest. What was the speed of the car before impact, assuming no energy is lost in the collision with the wall?

m/s
Jun 26th, 2015

The energy of a compressed spring is 0.5 kx^ 2 where k is the spring constant and x is the amount of compression so the energy of the spring is

E1 =  0.5 * 4.40* 10 ^ 6 * 2.95

E1 = 1914.55 J

Now this force stopped the automobile

Initial velocity u = ?

Final velocity v= 0

So change in energy is E2 = 0.5 m ( u^2 - v^2)

So m = 1000 kg

No E1 = E2

So on solving u = 1.95 m/ s

Please let me know if you need any clarification. I'm always happy to answer your questions.awaiting a positive feedback. thank you.
Jun 26th, 2015

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Jun 26th, 2015
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Jun 26th, 2015
Oct 22nd, 2017
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