Projectiles Flashcards
(16 cards)
Projectile motion
The movement of a body through the air following a curved path under the force of gravity
What forces act on projectles
-Weight
-Air resistance
Factors affecting distance travelled horizontally
- Speed of release
- Angle of release
- Height of release
- Aerodynamic factors
Speed of release
The primary reason for the horizontal distance
-The faster the speed of release, the further the body will travel
Angle of release
-Optimal angle of release = 45° if release height & landing height are the same (neutral), e.g. long jump
-65° when there is a negative relative release height (landing is higher), e.g. basketball shot
-35° when there’s a positive relative release height (landing is lower), e.g. shot put
Height of release
The higher the release, the greater the horizontal distance covered
Parabolic flightpath
A flight path symmetrical around its highest point caused by a dominant weight force of a projectile
Non-parabolic flight path
Asymmetrical around its highest point, caused by the dominant force of air resistance on the projectile
Projectile motion-free body digram
-weight + air resistance arrows always from COM
-Weight arrow vertically down
-Air resistance arrow in the opposite direction to motion
-Always include a direction of motion arrow
-If the RF arrow is closer to the weight arrow, it will represent a more parabolic shape. vice versa
Bernoulli’s principle
Lift force
-If the aerofoil is tilted at an angle of attack (17°)
-The air has to travel over the curved upper surface, so air has to travel further than air underneath
-Therefore, air is travelling at a greater velocity
-The faster the air travels, the lower the air pressure
-Air moves from high to low pressure
-Therefore, an unwards force is created and we have lift
E.g. ski jumping
When a down downward lift force is used
-Depends on angle of attack and shape of projectile
-Spoilers in F1 are shaped to allow downward lift force, pushing the car onto the track, increasing friction
Magnus effect
Spin
-To apply spin, one must apply an eccentric force
Hitting a ball with top spin
-Air passing over the ball is travelling in the opposite direction to the spin
-Causing air to decelerate, increasing pressure
-Air passing under the ball is travelling in the same direction as the spin
-Therefore, causing air to accelerate, lowering the air pressure
-Air moves from high to low pressure, causing the ball to dip downwards
Top spin
Eccentric force applied above the COM
-Spins downwards around the transverse axis causing dip
Back sp[in
Eccentric force applied below COM
-Spins upwards around transverse axis casuing lift
Sidespin-slice
Eccentric force applied left of the COM
-Spins right around the longitudinal axis, causing the object to move left to right
Sidespin-hook
Eccentric force applied to the right of the COM
-Spins left around the longitudinal axis, causing the object to move right to left
