Question

Consider projectile thrown horizontally at 50 m/s from height of 19.6 meters. The projectile will take ______________ time to hit the ground as it would if it were dropped from the same height.

a) More

b) Less

C)The Same

Answer 1

If projectile thrown horizontally, then

Initial vertical speed = 0, (Since projectile is thrown horizontally)

Vertical acceleration = +9.81 m/sec^2

Vertical distance travelled = 19.6 m

Using equation

Sy = Uy*t + 0.5*ay*t^2

19.6 = 0*t + 0.5*9.8*t^2

t = sqrt (19.6/(0.5*9.8)) = 2 sec

Time taken if projectile is dropped from same height

S = U*t + 0.5*a*t^2

S = 19.6 meter, a = +g = 9.8 m/sec^2

U = initial velocity = 0 m/sec, Since dropped

So,

19.6 = 0*t + 0.5*9.8*t^2

t = sqrt (19.6/(0.5*9.8))

t = 2 sec

So we can see that time will be same in both cases.

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