Launching at an angle

Science · Forces & Motion · ages 16-18

Name ______________________ Date ____________

A ball is kicked at 20 metres per second at 30 degrees. What is its starting upward velocity in metres per second?
Answer: ______________
What is the first step for a ball launched at an angle?
- Split the launch velocity into sideways and upward parts
- Find the range with a quoted formula
- Weigh the ball to find its mass
What is the horizontal acceleration during the flight?
- 9.8 metres per second squared down
- Zero
- 9.8 metres per second squared up
That launch starts with about 17 metres per second sideways. About what is the range in metres?
Answer: ______________
A ball launches at 19.6 metres per second at 30 degrees. Take g as 9.8. What is the total flight time in seconds?
Answer: ______________
What is the greatest height of that same launch?
- 2 m
- 9.8 m
- 4.9 m
On level ground a ball climbs for 1.5 seconds. What is its total flight time?
- 1.5 seconds
- 3 seconds
- 4.5 seconds
Which launch angle gives the longest range from a cliff top onto level ground below?
- Below 45 degrees, since the fall already runs long
- Exactly 45 degrees, as on level ground
- Above 45 degrees, to stay up longer

Answer key

For grown-ups. Fold this page away before handing over the rest.

10 · Upward is 20 times sin 30, which is 20 times 0.5.
Split the launch velocity into sideways and upward parts · Everything after depends on the two starting parts, so resolve first.
Zero · Gravity only ever acts vertically, so the sideways part cruises untouched.
34 · Range is sideways speed times flight time: 17 times 2 is 34.
2 · Upward is 9.8, so the climb takes 1 second and the flight doubles it.
4.9 m · Upward squared over 2 g is 96.04 over 19.6, which is 4.9.
3 seconds · Symmetry on level ground makes fall time match climb time.
Below 45 degrees, since the fall already runs long · The long fall rewards extra upward tilt less, so the best angle drops below 45.