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# Projectile Motion.......(help) watch

1. Please can someone help me to answer this question!!!! Explain to me in detail, by stating the equation used why the answer is C ...THANKS IN ADVANCE !!!!

A ball is projected horizontally from the top of a cliff on the surface of the earth with a speed of 40 m/s.Assuming that there is no air resistance, what will its speed be 3 s later?

A 30 m/s

B 40 m/s

C 50 m/s

D 60 m/s

E 70 m/s
2. I cant be bothered doing the actual maths to check but horizontal speed will remain constant as there is no air resistance. The ball will accelerate downwards at 9.8m/s^2. You then must essentially use Pythagoras on its vertical and horizontal velocities to find its speed.
3. If there is no air resistance the equation v=u+at can be used. and according to the equation the answer must be 70 and not 50....that's confusing....don't you think equation of motion must be used to find the solution
4. You sound very confused jinx. Why two threads for the same question?

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