# physics

posted by .

jack gives 50 kg jill a ride on a sleigh for 500 meters. he exerts a force of 45 Newtons on the rope of the sled at an angle of 30 degrees. He pulls her at a constant velocity. What is the coefficient of friction between the sled and the ground? How much work does he do on the sled?

• physics -

ok, im not good at physics but i'll give it a try. this may be a silly question but the ground they are on is snow right?

• physics -

yes i guess it would be snow

• physics -

The equation of motion is (in vector form)
vector (m•g) + vector F(fr)+ vector N+vectorF =0
Projections on the axes
x: F•cosα-F(fr) = 0
y: -mg+N+F•sinα = 0
F(fr) = F•cosα,
N =mg- F•sinα,
F(fr) = k•N =k•(mg- F•sinα),
F•cosα= k•(mg- F•sinα),
k = F•cosα/(mg- F•sinα) =
= 45•0.866/(50•9.8-45•0.5) = 0.083.
W= W(F) + W(fr)=F•cosα•s +F(fr) •s=
= F•cosα•s +k•N•s =
= s• (F•cosα + k•(mg - F•sinα)) =
=500 (45•0.866 + 0.083•(50•9.8 - 45•0.5)=38885 J

## Similar Questions

1. ### Physics

A boy pulls a sled with a force of 40N on a rope 2.5 meters long. The end that he holds is 1.5 meters higher than the end attached to the sled. What is the magnitude of the horizontal component that acts to pull the sled forward?
2. ### Pre-calculus

Nathaniel pulls a sled along level ground with a force of 30 newtons on the rope attached to the sled. If the rope makes an angle of 20 degrees with the ground when it is pulled taught, find the horizontal and vertical components of …
3. ### physics

A boy pulls a sled of mass 5.0 kg with a rope that makes an 60.0° angle with respect to the horizontal surface of a frozen pond. The boy pulls on the rope with a force of 10.0 N; and the sled moves with constant velocity. What is …
4. ### physics

A boy exerts a horizontal force of 2nt to pull his 2kg sled over the snow. If he gives someone a ride on his sled and he has to exert a 12nt force to pull the sled, how much does that person weigh and what is their mass?
5. ### Physics

A boy pulls a sled with a force of 40 N on a rope 2.5 meters long. The end that he holds is 1.5 meters higher than the end attached to the sled. What is the magnitude of the horizontal component that acts to pull the sled forward?
6. ### physics

an adult exerts a force of 26n to pull a child across the snow on a sled. The rope joins the sled at an angle of 30 degrees above the horizontal. Ignoring friction, how much work is done in pulling the sled 390m?
7. ### Physics

The sled is stuck in the snow. A child pulls on the rope and finds that the sled just barely begins to move when he pulls with a force of 24 N, with the rope at an angle of θ = 33° with respect to the horizontal. The mass of …
8. ### physics

a man pulls an 80 kg sled up an incline that is at an angle of 25 degrees with the horizontal using a rope attached to the sled at an angle of 35 degrees. If the coefficient of friction between the sled and the incline is 0.70, what …
9. ### Calculus

Susan pulls on a rope sleigh with a force of 120 N. If the rope makes an angle of 25 degrees with the horizontal, what is the force that tends to lift the sleigh?
10. ### Physics

A person exerts a force of 90 N on a rope that pulls a sled across a very smooth surface. The rope is oriented 37∘ above the horizontal. The sled has a total mass of 40 kg . The sled starts at rest and moves for 10 m.

More Similar Questions

Post a New Question