Projectile MotionProjectile Motion

Fact or Fiction Fact or Fiction For a fastball to travel at 90 mph, the For a fastball to travel at 90 mph, the

pitcher’s hand (or fingers) must be moving pitcher’s hand (or fingers) must be moving at 90 mph when the ball is releasedat 90 mph when the ball is released

The moon is constantly falling towards The moon is constantly falling towards EarthEarth

A coin dropped off a cliff will reach the A coin dropped off a cliff will reach the ground before another coin thrown ground before another coin thrown horizontally from the cliff at the same horizontally from the cliff at the same height.height.

ProjectileProjectile Object that is launched by a force and Object that is launched by a force and

continues to move by its own inertiacontinues to move by its own inertia Only force acting on object is gravityOnly force acting on object is gravity TrajectoryTrajectory- the path of a projectile - the path of a projectile

(parabola)(parabola)

Projectile MotionProjectile Motion

Horizontal (x) and Vertical (y) Horizontal (x) and Vertical (y) components are independent of each components are independent of each otherother

No force acts horizontally; Horizontal No force acts horizontally; Horizontal motion is motion is constant.constant.

Force of gravity acts vertically; vertical Force of gravity acts vertically; vertical motion is motion is acceleratedaccelerated

What does this mean?What does this mean?

Objects propelled horizontallyObjects propelled horizontally also fall also fall vertically at a rate of +9.8 m/svertically at a rate of +9.8 m/s22 (No matter (No matter how hard object is thrown) how hard object is thrown)

Horizontally launched object and one that is dropped

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

Rolling Ball off TableRolling Ball off Table

Projectiles have 2 Projectiles have 2 velocities- Horizontal and velocities- Horizontal and Vertical!Vertical!

   Force of gravity only acts verticallyForce of gravity only acts vertically

Vertical Velocity (VVertical Velocity (Vyy) - Force of gravity accelerates objects vertically ) - Force of gravity accelerates objects vertically at a rate of 10 m/sat a rate of 10 m/s22 downward. (So in the vertical direction the ball downward. (So in the vertical direction the ball slows down on the way up and speeds back up on the way down by slows down on the way up and speeds back up on the way down by 10 m/s every second)10 m/s every second)

Horizontal Velocity (VHorizontal Velocity (Vxx) ) In absence of air resistance, projectile maintains initial horizontal In absence of air resistance, projectile maintains initial horizontal

velocity it was given. (Inertia) velocity it was given. (Inertia)  VVxx is constant! is constant! VVixix = V = Vx x = constant = constant VVx x = d= dxx/t/t  

Objects that are thrown Objects that are thrown horizontallyhorizontally

only only one factorone factor determines the time in determines the time in air.air.  

Object's initial height (dObject's initial height (dyy))

t in air = t in air =

dy

Objects that are thrown Objects that are thrown horizontallyhorizontally

To find the maximum range (dTo find the maximum range (dxx) or ) or

horizontal displacement use the formula:horizontal displacement use the formula:

ddxx = v = vxxtt

Ex. A stone is thrown Ex. A stone is thrown horizontally at 7.5 m/s from horizontally at 7.5 m/s from a cliff that is 68.4 m high. a cliff that is 68.4 m high. How far from the base of How far from the base of the cliff does the stone the cliff does the stone land?land?

Draw a diagram of this situationDraw a diagram of this situation Break up information into x and y!Break up information into x and y! 27.8 m from the base of the cliff27.8 m from the base of the cliff

Ex. A baseball is thrown Ex. A baseball is thrown horizontally with a velocity horizontally with a velocity of 44 m/s. It travels a of 44 m/s. It travels a horizontal distance of 18 m horizontal distance of 18 m to the plate before it is to the plate before it is caught.caught.

A. How long does the ball stay in the air?A. How long does the ball stay in the air? B. How far does the ball drop during its B. How far does the ball drop during its

flight?flight? A = 0.41 sA = 0.41 s B = 0.82 mB = 0.82 m

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

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

Monkey and the Monkey and the tranquilizer guntranquilizer gun

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

Monkey & the Hunter

Thrown at monkey with Thrown at monkey with slow speedslow speed

Thrown at monkey with Thrown at monkey with fast speedfast speed

Does the moon fall in the Does the moon fall in the sky?sky?

Satellites areSatellites are

ProjectilesProjectiles that that fall fall around Eartharound Earth The The moonmoon is a satellite is a satellite GeosynchronousGeosynchronous orbits match the Earth’s orbits match the Earth’s

spinspin

Show what you knowShow 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 knowShow 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.