7.8- PROJECTILE MOTION 2 Flashcards
What will any form of motion where an object experiences a constant acceleration in a different direction to its velocity be like?
projectile motion
Example of something that will be a projectile path?
path of a ball rolling across an inclined board
How is the object projected on the inclined board?
across the top of the board from the side
What is the path of the ball rolling across an inclined board like? (2)
path curves down the board + is parabolic
Why is the path parabolic when a ball rolls across an inclined board?
object subjected to constant acceleration acting down on board + its initial velocity is across board
Another example of parabolic path?
path of a beam of electron directed between two oppositely charged parallel plates
What is each electron in the beam acted on by? (parabolic path)
constant force towards positive plate
Why is each electron in the beam acted on by a constant force towards the positive plate? (parabolic path)
as charge of an electron is negative
What does each electron experience due to the charge of the plate and itself? (parabolic path)
constant acceleration towards the positive plate
Why is the path of the electrons in the beam parabolic? (parabolic path)
its motion parallel to plates is zero acceleration whereas its motion perpendicular to plates is at constant (non-zero) acceleration
What does a projectile moving through air experience?
a force that drags on it
Why does a projectile moving through air experience a force that drags on it?
because of the air resistance of the air it passes through
What is the drag force that a projectile moving through air experience partly caused by?
friction between layers of air near projectile’s surface where air flows over surface
What direction does the drag force act?
opposite direction to direction of motion of projectile
When does the drag force increase?
increases as projectile’s speed increase
What does the horizontal component of the drag force do?
reduces horizontal speed of projectile + its range
What does the drag force do to the projectile’s maximum height if its initial direction is above the horizontal? (2)
reduces the maximum height + makes it descent steeper than its ascent
Why is the shape of the projectile important?
it affects the drag force + may also cause a lift force
When is a lift force caused?
if the shape of the projectile causes the air to flow faster over the top of the object than underneath it
What happens to pressure when air flows faster over the top of an object than underneath it?
pressure of the air on the top surface is less than that on the bottom surface
pressure difference causes lift force on object
What else experiences a force due to the shape, air flow and pressure?
spinning ball
What direction can the force be for a spinning ball?
downwards, upwards, or sideways, depending on how the ball is made to spin
What direction would a ball follow if it was projected into the air and gravity could be switched off + air resistance negligible?
follow a straight line with no change in velocity
Without gravity what would the horizontal component of an object’s velocity be?
Ucosθ
U- launch speed
θ- angle
Without gravity what would be the vertical component of an object’s velocity be?
Usinθ
U- launch speed
θ- angle
Without gravity what would be the horizontal component of displacement?
x = Utcosθ
If gravity was applied to the vertical component of velocity equation without gravity, what would it be?
y = Utsinθ - 1/2gt^2
If gravity was applied to the horizontal component of velocity equation without gravity, what would it be?
Vy = Usinθ - gt
