Hi there's a question thats been bugging me lately:
Lets say we throw a ball vertically upwards, If we assume that the only forces acting are Upthrust, Drag (frction due to air resistance and weight mg of ball. As the ball rises,
What happens to its velocity-- (well according to me it decreases)
How does the frictional force vary with time?
Thus how how is the deceleration affected?
How does the deceleration hence vary with time ( plz state how the rate of change of deceleration changes too) --> so that i can make a graph
Lets say we throw a ball vertically upwards, If we assume that the only forces acting are Upthrust, Drag (frction due to air resistance and weight mg of ball. As the ball rises,
What happens to its velocity-- (well according to me it decreases)
How does the frictional force vary with time?
Thus how how is the deceleration affected?
How does the deceleration hence vary with time ( plz state how the rate of change of deceleration changes too) --> so that i can make a graph
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Upthrust and weight are constants (within a reasonable distance above the Earth's surface), the drag force is dependent on speed .. decreasing to zero as the speed decreases to zero.
For velocity .. the net (resultant) force acting on the ball is against the motion (weight and air resistance) so there is a deceleration .. the velocity decreases.
Disregarding air resistance ,the retarding force is a constant weight force (mg) and the deceleration (neg.acceleration) is a constant rate.
Including air resistance, (which is greatest initially when velocity is greatest) .. the total decelerating force (weight + drag) is greatest initially and decreases as the drag decreases with the velocity.
So, over distance (or time) the rate of deceleration decreases .. being the unhindered value (g = 9.80m/s²) at the greatest height when (momentarily) the velocity is zero.
If you want to include upthrust (which generally really is negligible) .. then the net retarding force is very slightly reduced (as upthrust acts upwards) by a constant amount and the rate of deceleration (going upwards) and the rate of acceleration (going downwards) are slightly reduced.
Hope this covers all the points you asked about .. .. if not I'm sure Yuki's answer will fill in any missing bits !!☺
For velocity .. the net (resultant) force acting on the ball is against the motion (weight and air resistance) so there is a deceleration .. the velocity decreases.
Disregarding air resistance ,the retarding force is a constant weight force (mg) and the deceleration (neg.acceleration) is a constant rate.
Including air resistance, (which is greatest initially when velocity is greatest) .. the total decelerating force (weight + drag) is greatest initially and decreases as the drag decreases with the velocity.
So, over distance (or time) the rate of deceleration decreases .. being the unhindered value (g = 9.80m/s²) at the greatest height when (momentarily) the velocity is zero.
If you want to include upthrust (which generally really is negligible) .. then the net retarding force is very slightly reduced (as upthrust acts upwards) by a constant amount and the rate of deceleration (going upwards) and the rate of acceleration (going downwards) are slightly reduced.
Hope this covers all the points you asked about .. .. if not I'm sure Yuki's answer will fill in any missing bits !!☺
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The moon is a planet and planets don't think, that I'm aware of at least.