Projectiles And Its Application

CONTENTS

• Meaning of projectile
• Terms associated with projectiles
• Uses of projectile

MEANING OF PROJECTILE

A projectile motion is one that follows a curved or parabolic path .It is due to two independent motions at right angle to each other .These motions are

1. a horizontal constant velocity
2. a vertical  free fall due  to gravity

Examples of projectile motion are the motion of;

1. a  thrown rubber ball re-bouncing from a wall
2. An athlete doing the high jump
3. A stone released from a catapult
4. A bullet fired from a gum
5. A cricket ball thrown against a vertical wall.

USE OF PROJECTILES

1.    To launch missiles in modern warfare

2.    To give athletes maximum takeoff speed at meets

In artillery warfare, in order to strike a specified target, the bomb must be released when the target appears at the angle of depression φ given by: Tan φ =1/u  √gh/2  

CLASSWORK

1. (a) Define the term projectile (b) mention two application of projectiles
2. A ball is projected horizontally from the top of a hill with a velocity of 30m/s. if it reaches the ground 5 seconds later, the height of the hill is
3. A stone propelled from a catapult with a speed of 50m/s attains a height of 100m. Calculate: a. the time of flight b. the angle of projection c. the range attained.

ASSIGNMENT

SECTION A

1. A stone is projected at an angle 60 and an initial velocity of 20m/s determine the time of flight (a) 34.6s (b) 3.46s (c) 1.73s (d) 17.3s (e) 6.92s
2. A stone is projected at an angle 60 and an initial velocity of 20m/s determine the time of flight (a) 34.6s (b) 3.46s (c) 1.73s (d) 17.3s (e) 6.92s
3. For a projectile the maximum range is obtained when the angle of projection is; (a) 60⁰ (b) 30⁰ (c) 45⁰ (d) 90⁰
4. The maximum height of a projectile projected with an angle of   to the horizontal and an initial velocity of U is given by

(a)  U sin² θ    (b) U² sin²θ (c) U²sin θ (d) 2U²sin²θ

g                 2g               g                 g

Use this information to answer questions 5 and 6: An arrow is shot into space with a speed of 125m/s at an angle of 15⁰ to the level ground. Calculate the:

• Time of flight (a) 5seconds (b) 6.47seconds (c) 16.01seconds (d) 4.7seconds
• Range of the arrow (a) 350m (b) 781.25m (c) 900m (d) 250.71

SECTION B 

1. A gun fires a shell at an angle of elevation of 30⁰ with a velocity of 2x10m.  What are the horizontal and vertical components of the velocity? What is the range of the shell? How high will it rise?
2. (a) What is meant by the range of a projectile? (b) An object is projected into the air with a speed of 50m/s at an angle of 30⁰ above the ground level. Calculate the maximum height attained by the object