Physics

What will reach first to ground hail or water drop?

Correct me if I'm wrong I haven't done **** over summer holiday. Assuming that water and hail droplet are equal in mass and their shape is the same and constant during the fall then they should fall at the same rate. However, in general hail droplet seems to be heavier than water. Assuming that there is air resistance force that is proportional to V^2, the heavier hail droplet would drop with higher terminal velocity since more opposing force is needed to stop it from accelerating.

Reply 2

MagnumKoishi

21

Original post by CallMeJamesss

Correct me if I'm wrong I haven't done **** over summer holiday. Assuming that water and hail droplet are equal in mass and their shape is the same and constant during the fall then they should fall at the same rate. However, in general hail droplet seems to be heavier than water. Assuming that there is air resistance force that is proportional to V^2, the heavier hail droplet would drop with higher terminal velocity since more opposing force is needed to stop it from accelerating.

Hail may seem heavier than water, but it's the opposite. If you assume they're the same size, then the hail is actually lighter as ice is less dense than water.

That, and water will mould to the most aerodynamic shape as it falls, whereas the hail will not. So the water drop has a lower drag coefficient

The deceleration due to air resistance is inversely proportional to mass, and directly proportional to drag coefficient. Mass higher, drag coefficient lower = water will fall faster

(edited 4 years ago)

Reply 3

mnot

Universities Forum Helper

20

Original post by SaadSaeed

What will reach first to ground hail or water drop?

I suspect water. (assuming = mass).

Acceleration is equal, but the max velocity downwards will be determined by related to drag,
Drag coefficient will be larger in hail, due to less adaptable shape (coarse oval v tear drop)
Drag Area will be larger (frozen water is a larger volume, hence even 2D cross section will be larger

Drag force = 0.5 x density x Cd x A x Velocity^2

Peak velocity when weight = drag force, hence water drop will have a slightly higher peak velocity, although both should accelerate at equal rates.

Reply 4

CallMeJamesss

6

Original post by MagnumKoishi

Hail may seem heavier than water, but it's the opposite. If you assume they're the same size, then the hail is actually lighter as ice is less dense than water.

That, and water will mould to the most aerodynamic shape as it falls, whereas the hail will not. So the water drop has a lower drag coefficient

The deceleration due to air resistance is inversely proportional to mass, and directly proportional to drag coefficient. Mass higher, drag coefficient lower = water will fall faster

Sound about right ^^

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