A cannonball is shot (from ground level) with an initial horizontal velocity of
ID: 1593062 • Letter: A
Question
A cannonball is shot (from ground level) with an initial horizontal velocity of 36 m/s and an initial vertical velocity of 21 m/s.
1)
What is the initial speed of the cannonball?
m/s
2)
What is the initial angle of the cannonball with respect to the ground?
°
3)
What is the maximum height the cannonball goes above the ground?
m
4)
How far from where it was shot will the cannonball land?
m
5)
What is the speed of the cannonball 2.8 seconds after it was shot?
m/s
6)
How high above the ground is the cannonball 2.8 seconds after it is shot?
m
Explanation / Answer
1) ux = 36 m/s
uy = 21 m/s
speed = sqrt(ux^2 + uy^2)
= sqrt(36^2 + 21^2) = 41.68 m/s
2) @ = tan^-1(uy / ux) = 30.26 deg
3) maximum height is when vertical velocity will become zero.
using v^2 - u^2 = 2ad
0^2 - 21^2 = 2(-9.81)H
H = 22.48 m
4) for time period using v = u + at
-21 = 21 - 9.81t
t = 4.28 s
distance = 36 x 4.28 = 154.13 m
5. after 2.8 s
vx =ux = 36 m/s
vy = 21 - 9.81(2.8) = - 6.5 m/s
speed = sqrt(36^2 + 6.5^2) = 36.58 m/s
6) h = uy*t + ay*t^2 /2
h = 21*2.8 + (-9.81 * 2.8^2 /2 )
h = 20.34 m
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