Retrieval Practice
Projectile Motion — AQA A-Level Physics
Q1. What is meant by the independence of horizontal and vertical components in projectile motion?
- The horizontal and vertical motions are independent: gravity only affects the vertical component, and horizontal velocity stays constant (no air resistance).
- They are linked only by time.
Q2. How do you resolve the initial velocity of a projectile launched at angle theta?
- Horizontal: u cos(theta).
- Vertical: u sin(theta).
Q3. What is the vertical velocity at the maximum height of a projectile?
Zero.
Q4. How do you find the time of flight for a symmetric projectile?
Time of flight = 2u sin(theta) / g.
Q5. Write the equation for the maximum height of a projectile.
H = (u sin theta)^2 / (2g).
Q6. At what angle is the range of a projectile maximised (no air resistance)?
45 degrees.
Q7. For horizontal projection, what is the initial vertical velocity?
Zero.
Q8. How does air resistance affect the trajectory of a projectile?
- It reduces the range and maximum height.
- The descent is steeper than the ascent, and the trajectory is no longer a symmetric parabola.
Q9. What SUVAT equation would you use to find the time for a horizontally projected object to fall height h?
s = ut + 0.5at^2 with u = 0, giving h = 0.5gt^2, so t = sqrt(2h/g).
Q10. What acceleration acts on a projectile horizontally (ignoring air resistance)?
- Zero.
- There is no horizontal force, so horizontal velocity is constant.