A) Your nephew has just received an air-rifle as a birthday present. He wants to

Question

A)Your nephew has just received an air-rifle as a birthday present. He wants to know, of course, how fast the BB shot (the projectile) is traveling as it leaves the rifle.
You demonstrate your knowledge of physics and, it follows, everything of importance, by helping him set the rifle vertically and, making sure you both have adequate headgear, fire the rifle. You then time the landing of the shot nearby, finding it to be 6.30 seconds after pulling the trigger. You then confidently announce that the speed of the BB as it left the rifle was at least x km/h.
What is x, in km/h?

B)You go on to further demonstrate your prowess in physics by setting up the rifle at the edge of a lake at an angle of 30.0 degrees upwards (with respect to the horizontal) and then predicting how far out into the lake the shot will land. What is your prediction, in meters? (You neglect details as air resistance)

Explanation / Answer

Part A)
Apply vf = vo + at

2v = (9.8)(6.3)

v = 30.87 m/s

That converts to 111.1 km/hr

Part B

R = vo^2sin(2angle)/g

R = (30.87)^2(sin 60)/9.8

R = 84.2 m

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