Physics Questions! Please Help :)?

Question

A very tall man whirls a 0.5kg stone on the end of a 2.0 m length of fishing line which has a breaking strain of 25 N. He whirls the stone 2.45 metres above the ground, faster and faster. Eventually, the fishing line breaks and the stone flies off horizontally as a projectile. Find the following:

1) The time of flight of the stone.

2) How far from his feet the stone lands.

Please show working and explain clearly what you're doing.

Thanks a lot!

Answer 1

Firstly you need to calculate the time it takes to hit the ground.

You know the height from the ground, and the acceleration (9.8 m/s2)

Formula is

s = ut + 0.5at^2

2.45 = 0 + 0.5 x 9.8 x t^2

t^2 = 2.45 / 4.9 = 0.5

t = 0.7071 seconds

Now we can use this to work out the distance travelled.  The stone breaks away with 25N of force, 2 metres away from the person, and is in flight for 0.7071 seconds

F= ma

25 = 0.5 a

initial acceleration is 25/0.5 = 50 m/s^2

s = ut + 0.5at^2

s = 0 + 0.5 * 50 * (0.7071)^2

s = 12.5 metres

Now you need to add the extra 2 metres for the length of fishing line

distance = 12.5 + 2 = 14.5 metres

Answer 2

28 seconds

62 metres