1. A projectile is launched from the ground level at a velocity of 28 m/s, 57 de
ID: 2118867 • Letter: 1
Question
1. A projectile is launched from the ground level at a velocity of 28 m/s, 57 degrees above the horizontal, towards a building 65 m away. The buidling has a 2.0-m tall open window facing the launch point, with a bottom edge 14 m above the ground.
Question: Will the projectile go in the open window, or hit the wall of the building? Assume that it won't hit to the right or left of the window, and won't hit the ground. Air resistance is negligible.
2. A 270-kg crate is at rest on a ramp inclined 11 degrees above the horizontal. A man is standing on the ramp above the crate, and is trying to push it down the ramp. The coefficient of static friction between the crate and the ramp is 0.46, and the maximum force he's able to exert on the grate (directed parallel to the ramps surface) is 600 N (6.0x10^2 N)
Question: Will he be able to push the crate down the ramp?
Explanation / Answer
1.
initial speed of projectile is u = 28 m/s
the angle is A = 57o
the range of projectile is
R = (u^2 x sin(2A)/g)
where g = 9.8 m/s^2
the distance of the building is S = 65 m
If R > S then the projectile hits the window
2.
the mass of the crate m = 270 kg
the angle is A = 11o
the coefficient of static friction is u_s = 0.46
the man is able to push with a force F = 600 N
the required force on the crate to move it is
w = u_s x m x g x cos(A)
where g = 9.8 m/s^2
If F > w then the man will be able to push the crate
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