- #1

Iamconfused123

- 66

- 9

- Homework Statement
- A car of mass 1000 kg hits the spring with a speed of 10 m/s and condenses it by 1 m. If we disregard the friction, what is the resistance constant of the spring?

- Relevant Equations
- ##E_p=\frac{kx^{2}}{2}##, ##E_k=\frac{mv^2}{2}##

Can someone please tell me where I am wrong?

I tried to solve the problem using velocity equation; ##v_{f}^2= v_{i}^{2} + 2as## and got a= 50m/s^2, F= 50 000N and therefore F=kx -> k=50 000N/m because dx=1.

But it's not correct. When I do it using conservation of energy I get 100 000N/m. Which is correct according to the solutions.

##\frac{mv^2}{2}=\frac{kx^2}{2}## -> k=100 000N/m.

Thank you.

I tried to solve the problem using velocity equation; ##v_{f}^2= v_{i}^{2} + 2as## and got a= 50m/s^2, F= 50 000N and therefore F=kx -> k=50 000N/m because dx=1.

But it's not correct. When I do it using conservation of energy I get 100 000N/m. Which is correct according to the solutions.

##\frac{mv^2}{2}=\frac{kx^2}{2}## -> k=100 000N/m.

Thank you.