This might be a little tough if you haven't seen calculus before but the idea is the following: you know how velocity is rate of change of position? This is expressed as:
$$ v(t) = \frac{d[x(t)]}{dt} $$
Notice this is similar to the v = \frac{\Delta x}{\Delta t} equation. That symbol by...
Consider a differential element of mass dm. If you draw a figure, you will realize (if you think about it long enough) that this must be related to the area by:
$$ dm = 2\pi ada\sigma $$
Since you can imagine you have a disc which you added a small width increase da. You'll end up with a...
Your reasoning is correct, there's no need for the kinetic energy equations precisely because you know the angles they went off on. It's really just a way to test your understanding, to make sure you appreciate the underlying concept (conservation of linear momentum) by changing the usual form...
The main idea is to remember that you can decompose this type of motion (known as projectile motion) into two parts; the motion in the vertical direction and the motion in the horizontal direction. If you take the origin of your coordinate system to be ground (assuming falsely that Romeo has...