Projectile Motion (OCR AS Physics)

Revision Note

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Katie M

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Katie M

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Vertical & Horizontal Motion of a Projectile

  • The trajectory of an object undergoing projectile motion consists of a vertical component and a horizontal component
    • These need to be evaluated separately

  • Some key terms to know, and how to calculate them, are:
    • Time of flight: how long the projectile is in the air
    • Maximum height attained: the height at which the projectile is momentarily at rest
    • Range: the horizontal distance travelled by the projectile

Projectile Motion, downloadable AS & A Level Physics revision notes

How to find the time of flight, maximum height and range

Problems Involving Projectile Motion

  • There are two main considerations for solving problems involving two-dimensional motion of a projectile
    • Constant velocity in the horizontal direction
    • Constant acceleration in a perpendicular direction

  • The only force acting on the projectile, after it has been released, is gravity

 

  • There are three possible scenarios for projectile motion:
    • Vertical projection
    • Horizontal projection
    • Projection at an angle

Worked example

To calculate vertical projection (free fall)

A science museum designed an experiment to show the fall of a feather in a vertical glass vacuum tube.

The time of fall from rest is 0.5 s.

WE - Projectile Motion Worked Example 1 question image, downloadable AS & A Level Physics revision notes

What is the length of the tube, L?

WE - Projectile Motion Worked Example 1 answer image, downloadable AS & A Level Physics revision notes

Worked example

To calculate horizontal projection

A motorcycle stunt-rider moving horizontally takes off from a point 1.25 m above the ground, landing 10 m away as shown.

What was the speed at take-off?

WE - Projectile Motion Worked Example 2 question image, downloadable AS & A Level Physics revision notes

WE - Projectile Motion Worked Example 2 answer image, downloadable AS & A Level Physics revision notes

Worked example

To calculate projection at an angle

A ball is thrown from a point P with an initial velocity u of 12 m s-1 at 50° to the horizontal.

What is the value of the maximum height at Q?

WE - Projectile Motion Worked Example 3 question image, downloadable AS & A Level Physics revision notes

WE - Projectile Motion Worked Example 3 answer image, downloadable AS & A Level Physics revision notes

Examiner Tip

Make sure you don’t make these common mistakes:

  • Forgetting that deceleration is negative as the object rises
  • Confusing the direction of sin θ and cos θ
  • Not converting units (mm, cm, km etc.) to metres

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Katie M

Author: Katie M

Expertise: Physics

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.