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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