4. Projectile Motion

Question 1

What is a Projectile?

Answer 1

an object/body thrown, pushed, forced, released or dropped, and at the moment its launched, there is no forces acting on it besides wind and gravity.

Question 2

Why are vertical and horizontal components analyzed seperately?

Answer 2

The 2 are independent of each other.

• gravity only influences vertical motion
• Air Resistance only influences horizontal motion

Question 3

Try graphing the vertical components of the ball as it’s thrown straight up into the air

Answer 3

Question 4

What is Drag force in the Vertical direction?

Answer 4

Projectiles continue to accelerate while in free fall
As the speed of the system increases, an upward air resistance is created

This drag force (a type of friction) also acts on the system

Eventually, the drag force will equal the gravitational pull on the system

Question 5

What is terminal Velocity?

Answer 5

Terminal velocity is the constant speed that an object reaches when the force of gravity pulling it downward is balanced by the air resistance pushing upward, resulting in no further acceleration.

Question 6

Try graphing the horizontal components of the ball as it’s thrown from one hand to the other

Answer 6

Question 7

Describing Projectile Motion

Answer 7

Question 8

What are the components of Intital Velocity?

Answer 8

• Projection Speed
• Projection Angle
• Relative Projection Height

Question 9

The size and shape of trajectories for an object projected at 10 m/s at different angles is shown below

Answer 9

Question 10

How should a projectile be released if the goal is to reach a maximum height?

Answer 10

If the goal is to achieve maximum height

• The angle of projection is 90 ̊
• Projectile travels straight up / down (vertical trajectory)

Question 11

When should the angle of projection be Above 45º?

Answer 11

If the goal is to translate AND maximize the flight time in the air:

• Initial vertical velocity is greater than the horizontal velocity
• The angle of projection is above 45 ̊
• Projectile climbs to a point then begins to fall (oblique trajectory)

Question 12

When should the angle of projection be Below 45º?

Answer 12

If the goal is to minimize the flight time in the air

• The angle of projection is relatively small (i.e., below 45 ̊)
• If the projection angle is 0 ̊, the system simply drops (horizontal trajectory)

Question 13

Optimal Angles to Acheive different objectives:

Answer 13

Optimal angle is 45°

• If take off and landing heights are equal

Optimal angle is > 45º

• If landing is above the release height

Optimal angle is < 45º

• If landing is below the release height

Question 14

Would a bullet fired horizontally from a gun, or another bullet dropped from the same height, hit the ground first?

Answer 14

Same time since vertical velocity is independent of