A magpie, flying horizontally at a speed of 12 m / s, drops a coin it holds in its beak. The coin

touches the ground with a velocity equal to modulus of 20 m / s. At what height does the magpie

approximately fly?

A). 13 m

B). 8 m

C). 20 m

D). 26 m

E). It is not possible to answer because the mass of the coin is not known.

Hi guys!

I’m not getting answer option A and also I didn’t quiet understand what it means by “equal to the **modulus** of 20”

Please help me out. Thanks

Hi! You don’t need to worry about that, the translation technically means “the value”.

So we can use v^2=u^2 + 2as

the initial speed is 12 m/s and the final is 20 m/s.

20^2 =12^2 + 2x10xs

s = (400-144)/20 = 12.8 m which is approximately 13m

Hope this helps :))

Thank you soo much Raya got it now:)

Hi!

How come we can say u=12? I thought the bird speed would only be horizontal so u=0?

well here they say speed, not velocity so the direction doesn’t matter, if the magpie is flying at a certain speed, since the coin is in his mouth, it’s also moving at a certain speed, it’s not in one position in the air. I hope that makes sense haha, but I get your point as the vertical velocity is 0. THEN they say velocity modulus to specify it’s in the direction towards the ground