- #1

zesi

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## Homework Statement

Consider a cannonball being fired with a velocity of 30m/s from a cliff of height 45m.

http://imgur.com/OCMNEPv

(a) Calculate the time taken for the ball to reach the ground.

(b) Calculate the range of the motion.

(c) Calculate the horizontal velocity, vertical velocity, and the velocity of the cannon ball as it touches the ground.

## Homework Equations

4 kinematics formula.

## The Attempt at a Solution

(a) using s=vt+0.5at^2

I found out t=3.0sI am having a hard time with (b) and (c) because it is traveling in an arc. I am not sure how I should proceed.

(b) I don't think I can assume the calculation that it travels in a straight line down, then use trigonometry to find the range. What other ways can I think of?

(c) If I use "v(f) = v(i) + at" then it will the final velocity will be 60m/s, assuming acceleration (due to gravity) = 10m/s^2. However is this 60m/s the vertical velocity or the velocity as it touches the ground?

From my understanding v(f) = 60m/s is the vertical velocity. Once I have the range (horizontal distance) I can use it to find the horizontal velocity. Using vector concept, taking

vertical velocity - horizontal velocity

= velocity as it touches the ground.

I am having a hard time figuring out the horizontal distance.

Correct me if I am wrong.

Which concept am I not getting it? Hope someone can help me. Thank you.

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