Lecture 5 - projectile motion Flashcards by Jenny Lee

What is projectile

Any object in free fall and affected only by gravity and air resistance

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Trajectory is

Flight path of projectile (the arch)(predicable motion)

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Release is when

Objects begins projectile motion

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Apex is

The highest point in trajectory

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Projectiles have…?

Velocity

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Horizontal component for projectile from when we release it until it stops will be changing or constant?

Constant

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The vertical component will be constant or changing

Change

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What affects the vertical displacement/apex/ depends on

Vertical velocity

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What depends on projection angle

Magnitude of projectile motion

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The x component and y component of projectile motion are dependent or independent?

Independent of each other (separate)

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Airborne motion is always these 3 rules

Parabolic path of CoM
Constant horizontal velocity
Constant vertical acceleration

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Gravity influences Vx or Vy

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As the object is moving up, Vy is

Decreasing

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When the object is at apex the Vy is going to be

Zero

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When object is moving down, the Vy is going to be

Increasing

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When object is going up the gravitational force is going to be

-9.81 m/s^2

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When object is going down the gravitational force is going to be

9.81 m.s^2

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Trajectory of centre of mass (CoM) of projectile is always

Parabolic regardless of motion of body seamen’s

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Trajectory of centre of mass (CoM) of projectile is always

Parabolic regardless of motion of body segments

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What are the 3 different factors that can change projectile motion and how far the object moves

projectile height of release (relative height)
projection angle (angle of release)
projectile velocity (velocity of release)

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Anything that is being thrown at a higher place, the object will have. A longer or shorter time in the air

Longer flight time

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If we have a constant projectile velocity and a constant angle but we alter projectile height, what will happen?

Increase flight time = increase horizontal displacement

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Horizontal displacement is dependent on how long

You spend in the air (flight time) ex. At longer period of time but same velocity will result in a longer distance

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If release height is the same as landing height will foes it mean? Add pic

Time to apex= time to land

Vy release = Vy landing

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Release height > landing height ad pic

Time of apex < time to land

Release height < landing height add pic

Time to apex > time to land | Vy release > Vy landing

If the projection angle is 90 (shot straight up) all the velocity would be on

Vy and Vx=0

Projection angle influences shape of ______

Projectile’s trajectory

If projection angle is between 0 and 90 it will create

Parabolic trajectory will have every things listed for projectile motion

If projection angle = 0, if the release height is> landing height will have

1/2 parabola trajectory and Vy initial = 0

If you had the same weight of bricks and feather which will drop first? Why?

Both fall the same time because air resistance is zero, gravity will affect the same way since they are falling from the same height

If you want to maximize your vertical displacement you want to make your angle as?

Steep as you can closer to 90 degree

Maximize horizontal displacement you want to make your angle depend on

Optimal angle (height of release)

For projection height Release height = landing height —> optimal angle is Release heighT>landing height —> optimal angle is Release heighT < landing height —> optimal angle is

45 <45 >45

Why is 45 the optimal angle

By having the same release height and landing height and the angle is 45 it will maximize flight time and horizontal velocity

Projectile velocity determines

Magnitude of vertical and horizontal displacement

What is the most important factor in changing projectile motion

Projectile velocity

A potato cannon has a fixed angle of 50 degree relative to the ground. How can we alter the firing distance (displacement over time) if the angle is fixed?

Cannot move or change height, We can increase the projectile velocity or

A cannon with a fixed to the ground fires with a velocity of 1000m/s. How do we alter this cannon’s firing distance?

We have a fixed height and velocity Alter the projection angle to optimal angle

Example needing maximize vertical displacement?

High jump, pole vault (steep projection angle)

Maximize horizontal displacement?

Long jump, triple jump (small projection angle)

Example for when release ht=landing ht —> optimal projection = 45

Kick.a soccer ball for max horizontal displacement

Example for when release ht>landing ht —> optimal projection < 45

Throwing a baseball for max horizontal displacement

Example for when release ht optimal projection > 45

Chip into an elevated green (golf)

A cannon fires with a fixed angle of 50 and fixed velocity of 1000m/s. How do we alter the cannon’s firing distance?

Alter projectile height and increase it = increase horizontal displacement

Changing projectile height (increasing it) will only affect

Time of object going down

Total time can help figure out your

Horizontal displacement

Time total is

Time up + time down

Flight time is influenced by

Vy intital and projectile height

Horizontal displacement is influenced by

Vx time in air

Vertical displacement is influenced by

Vy initial, projectile height

Trajectory is influenced by

Initial velocity (magnitude), projection angle and projectile height

When analyzing horizontal components the Acceleration is 0

1. Vf=Vi+at —> vf=vi 2. D=Vit +1/2 a^2 -> d=Vit 3. Vf^2 = Vi^2 +2ad —> Vf2=Vi2

Anazlying when dropping a ball from a given height its a=-9.81 m/s^2

Vi=0 1. Vf=Vi+at —> vf=at 2. D=Vit +1/2 a^2 -> d=1/2at^2 3. Vf^2 = Vi^2 +2ad —> Vf2=2ad

Analyzing vertical components when at apex

1. Vf=Vi+at —> 0=Vi+at | 3. Vf^2 = Vi^2 +2ad —> 0=.Vi2+2ad

Time up Vy=Vf is

Zero

When time down, Vy=Vi is

Zero

A ball is thrown in the air with an initial velocity of 30 m/s and a horizontal velocity of 5 m/s. What was the maximal height reached by the ball? Vertical displacement

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A football is kicked with the initial horizontal velocity of 18 m/s and a flight time of 2s. How far will the ball travel?

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A ball is kicked with the initial horizontal velocity of 35 m/s and a vertical velocity of 10 m/s. how far will the ball travel

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A soccer player kicks a ball. The ball leaves the foot at a 23° angle relative to the horizontal, with a velocity of 58 m/s. The ball is in the air for 0.83 seconds. A) What is the ball’s vertical and horizontal velocity immediately after release? B) What is the ball’s max horizontal displacement? C) What is the ball’s vertical velocity at max vertical displacement? D) What is the ball’s max vertical displacement? E) What is the ball’s horizontal velocity just prior to contact time? F) What is the ball’s vertical velocity just prior to contact time?

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You hit a golf ball. The ball leaves the ground at 25 m/s at an angle of 60° from the ground. A) What is the maximum height the ball reaches? B) How much time does it spend in the air? C) How far does the ball travel?

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You hit onto an elevated green, which has a rise of 3m. You hit the ball at 45 m/s at an angle of 55°. A) How high does the ball travel? B) How much time does it spend in the air? C) How far does the ball travel?

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When the optimal angle is > 45 what happens

Release height < landing height

Optimal angle is < 45

Release height > landing height

When optimal angle is 45 what happens

Release height = landing height