Two motions at once.

Step 1 of 4

Watching the flight

The cannon fires a ball at $45^\circ$⁠, with no air. The ball leaves a ghost every quarter of a second, so you can compare what happened over equal stretches of time.

Look at the sideways gaps between the ghosts, along the field. Then answer the question.

Step 2 of 4

Splitting the velocity in two

Split the velocity is now On: each ghost has two arrows.

• The blue arrow is the horizontal part, $v_x = v\cos\theta$⁠. There is no horizontal force, so it keeps the same length for the whole flight.
• The orange arrow is the vertical part, $v_y = v\sin\theta - g t$$v_y =$$v\sin\theta - g t$⁠. It shortens on the way up, vanishes for a moment, flips on the way down, and changes by 9.81 m/s every second.

The two motions do not get in each other’s way: across, it is motion at a constant speed; up and down, it is motion with constant acceleration, just like the cart in the last lesson.

Try it: change the Launch angle. A low angle gives a long blue arrow and a short orange one; a high angle does the opposite.

Back to the experiment ↑

Step 3 of 4

What happens at the top

The angle is now $60^\circ$⁠, and Split the velocity is hidden until you have made your prediction. Think about the two parts separately: what is left of each one at the highest point?

Step 4 of 4

And what about mass?

The Scene has no mass control. Nothing is missing: without air, the ball’s path does not depend on its mass at all.