# Projectile Motion.

## Presentation on theme: "Projectile Motion."— Presentation transcript:

Projectile Motion

Fact or Fiction For a fastball to travel at 90 mph, the pitcher’s hand (or fingers) must be moving at 90 mph when the ball is released The moon is constantly falling towards Earth A coin dropped off a cliff will reach the ground before another coin thrown horizontally from the cliff at the same height.

Projectile Object that is launched by a force and continues to move by its own inertia Only force acting on object is gravity Trajectory- the path of a projectile (parabola)

Projectile Motion Horizontal (x) and Vertical (y) components are independent of each other No force acts horizontally; Horizontal motion is constant. Force of gravity acts vertically; vertical motion is accelerated

What does this mean? Objects propelled horizontally also fall vertically at a rate of +9.8 m/s2 (No matter how hard object is thrown) Horizontally launched object and one that is dropped

Rolling Ball off Table If we push the ball harder, giving it greater ___________ velocity as it rolls off the table, the ball takes _____ time to fall to the floor. Draw the new trajectory

Rolling Ball off Table

Projectiles have 2 velocities- Horizontal and Vertical!
Force of gravity only acts vertically Vertical Velocity (Vy) - Force of gravity accelerates objects vertically at a rate of 10 m/s2 downward. (So in the vertical direction the ball slows down on the way up and speeds back up on the way down by 10 m/s every second) Horizontal Velocity (Vx) In absence of air resistance, projectile maintains initial horizontal velocity it was given. (Inertia)  Vx is constant! Vix = Vx = constant Vx = dx/t

Objects that are thrown horizontally
only one factor determines the time in air.  Object's initial height (dy) t in air = dy

Objects that are thrown horizontally
To find the maximum range (dx) or horizontal displacement use the formula: dx = vxt

Ex. A stone is thrown horizontally at 7. 5 m/s from a cliff that is 68
Ex. A stone is thrown horizontally at 7.5 m/s from a cliff that is 68.4 m high. How far from the base of the cliff does the stone land? Draw a diagram of this situation Break up information into x and y! 27.8 m from the base of the cliff

Ex. A baseball is thrown horizontally with a velocity of 44 m/s
Ex. A baseball is thrown horizontally with a velocity of 44 m/s. It travels a horizontal distance of 18 m to the plate before it is caught. A. How long does the ball stay in the air? B. How far does the ball drop during its flight? A = 0.41 s B = 0.82 m

What will happen if a pilot drops a package when the plane is directly over the target?

The trajectory of a projectile launched upwards looks like...

Monkey and the tranquilizer gun
A scientist needs to shoot the monkey with a tranquilizer gun, but he knows that as soon as he shoots the gun, the monkey will let go of the tree and fall to the ground. Should he aim (above, beneath, or straight at) the monkey? Monkey & the Hunter

Thrown at monkey with slow speed

Thrown at monkey with fast speed

Does the moon fall in the sky?

Satellites are Projectiles that fall around Earth
The moon is a satellite Geosynchronous orbits match the Earth’s spin

Show what you know 1. A projectile’s motion is...
a. linear. b. one-dimensional. c. two-dimensional. d. three-dimensional. 2. A projectile’s horizontal motion is... a. uniform (constant). b. accelerated. c. absent.

Show what you know 3. The vertical component of a projectile’s motion is... a. uniform (constant). b. accelerated. c. absent. 4. A boy is riding a skateboard along a smooth, flat street. If he jumps straight up off the board, he will land... a. in front of the board. b. behind the board. c. on the board.