A 480kg cannon fires a 10kg cannonball with a speed of 200m/s relative to the muzzle. The cannon is on wheels that roll without friction. When the cannon fires, what is the speed of the cannonball relative to the earth?

Question

nottim · Answer

So I got -9600m/s, which doesn't seem close.

nincompoop · Answer

what is relative to the earth? 
you want to do a ratio of the earth's velocity revolving the sun?

nottim · Answer

I think its the cannon relative to the earth, yes?

nincompoop · Answer

what is the earth's velocity?

nottim · Answer

I'm assuming 0?

anonymous · Answer

abcd is a parallelogram in which angle adc=75 degree and side ab is produced to point e

nottim · Answer

Wrong area to post man.

nottim · Answer

Both in terms of question and section.

unklerhaukus · Answer

i think its just 

conservation of momentum $$\large m_\text{cannon}v_\text{cannon}=m_\text{ball}v_\text{ball}$$

the speed of the ball relative to the ground is $v_\text{ball}-v_\text{cannon}$

nottim · Answer

$$v _{\bf}=(480kg)(200m/s)/10$$ That's what I did, but it is incorrect.

nottim · Answer

v=9600 m/s

unklerhaukus · Answer

i think you've mixed up the masses

nottim · Answer

Would 4.16 make sense? Its still not like the textbook.

nottim · Answer

The textbook doesn't have the exact same question, but it is similar, and the answer was 196 m/s there.

unklerhaukus · Answer

yeah the velocity of tha cannon (relative to centre of mass) is $v_\text{cannon}=4.167[\text{m/s}] $


the velocity of the ball relative to the earth is    200 [m/s] -  v_cannon