25092020 Equations of Motion 3 Objects Projected Horizontally

25/09/2020 Equations of Motion 3 - Objects Projected Horizontally Summary Notes page 5.

What are we learning today? �How to explain the curved path of a projectile in terms of the force of gravity. �How projectile motion can be treated as two independent motions. �How to solve numerical problems for an object projected horizontally.

Projectile Motion �A projectile is an object which moves under the influence of two distinct types of motion, horizontal motion and vertical motion. �There a variety of examples of projectiles: 1. an object dropped from rest 2. an object thrown vertically upwards 3. an object thrown horizontally 4. an object thrown upwards at an angle.

Horizontal Projectiles (projectiles at an angle will be considered in the next lesson) �When an object is projected horizontally it immediately begins to fall vertically downwards under the influence of gravity. �Each type of motion acts independently of the other which causes the object to take a curved (parabolic) path.

Consider the effect of each type of motion: �Horizontal - unaffected by gravity and we can ignore air resistance. The horizontal speed remains constant. �Vertical - is affected by gravity. The initial vertical speed is zero. It will accelerate at 9. 8 ms-2. Use equations of motion.

Activity

Example A cat jumps horizontally out of a window with a speed of 5 ms-1. It takes 1. 5 s to reach the ground. a) State the final horizontal speed of the cat. b) Calculate the final vertical speed of the cat. c) Calculate the total horizontal distance travelled by the cat. d) Calculate the total vertical distance travelled by the cat.

Structured Problems page 10 Qs 23 -29.