Answer:
Well it would be equal to 500N because pushing forward the ball (or whatever maybe a body) would push the canon back an even 500N backwards...
Explanation:
How can I help? What’s the question?
Answer:
Average speed is 60 km/hour
Explanation:
When we need to calculate average speed, we use this equation:

Where:
position at the beginning
at the end


Then: 

Finally V = 60 km/hour