The person's horizontal position is given by
and the time it takes for him to travel 56.6 m is
so your first computed time is the correct one.
The question requires a bit of careful reading, and I think there may be a mistake in the problem. The person's vertical velocity 
at time 
is
which tells us that he would reach the ground at about 
. In this time, he would have traveled
But we're told that he is caught by a net at 56.6 m, which would mean that the net cannot have been placed at the same height from which he was launched. However, it's possible that the moment at which he was launched doesn't refer to the moment the cannon went off, but rather the moment at which the person left the muzzle of the cannon a fraction of a second after the cannon was set off. After this time, the person's initial vertical velocity 
would have been a bit smaller than 
.
As for me, there are two suitable answers for the question represented above and here is a short explanation why I consider these two to be correct :
D. The horizontal velocity of the projectile and <span>B. The length of time before it lands
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-- this led me to answers! Hope everything is clear! Regards!<span>
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Work = force x distance
200 Newtons x 20 meters
= 4,000 Joules
Newton's first law is sometimes known as the law of inertia. It is the law that states that an object at rest will stay at rest and an object in motion will stay in motion unless a force acts upon it. For example, if I was working with a wrench in space an it slipped, it would keep on going in one direction with a constant speed unless it hits something. Hope this helps!
