Recent content by ap123

You should repeat your initial calculations using kg instead of g (as pointed out in post #2). You will then get the correct answer.

You've written the nm part for the wavelength, but did you include it in the calculation?

Hello madayag1 Look again at the figure you've used for the wavelength - you forgot the nm. Also, the first part of the calculation is in J, but you've subtracted a value in eV from it.

An alternative (and easier) way of doing this is to use the impulse-momentum theorem.

I think it's just the diagram - e.g. the right angle at the bottom is not accurate.

It looks a little shorter, but how accurate is the diagram?

Your answers look correct to me.

J is the impulse

Good :-) We don't know F and t, and the initial momentum is zero, so just write J = P Apply this to the first and second wagons individually and to the 2 joined wagons and see what you get.

Then, what's the relation between impulse and momentum change?

What's the relation between force, time and momentum change?

So, what happens to the keys after this?

To put it in another way, how long does it take the keys to reach their highest point, ( you can easily get this from your answer to part (a) )

Would would happen if she didn't catch the keys on the way up?

You can use the constant-acceleration equations to work this out.