posted by mw .
An object with a mass of 49 N falls out of a plane going 20.0 m/s at 300 m above the ground.
1)How do I find the time that the object is in the air?
2)The horizontal distance of the object?
Could someone help me out?
N means Newtons and is FORCE, in this case of gravity (the "weight").
The mass is in KILOGRAMS
and the force 49 N = m g = m (9.8) approximately on earth.
HOWEVER - luckily in this problem all of that matters not at all. It does not matter what the mass or weight is at all. It accelerates downward at 9.8 m/s^2 and keeps going at 20 m/s horizontally.
distance down = (1/2)(9.8) t^2
300 = 4.9 t^2
t = 7.82 seconds in the air
now multiply that by 20.0 m/s to find the horizontal distance.
(Notice that the bomb hits right under the plane if the plane keeps going at 20 m/s straight. Always bank and climb after dropping bombs.)