Question

An 80 N crate slides with constant speed a distance of 5.0m downward along a rough slope that makes an angle of 30° with the horizontal. The coefficient of kinetic friction between the crate and the supporting material is 0.05. The work done by the force of gravity is:













A.
-400 J








B. -200 J







C. 400 J





D. 200 J



E.
-69 J​

Answer 1

Answer:

An 80 N crate slides with constant speed a distance of 5.0m downward along a rough slope that makes an angle of 30° with the horizontal. The coefficient of kinetic friction between the crate and the supporting material is 0.05. The work done by the force of gravity is: ans C

Answer 2

Option D : The work done by gravity in the given setup is 200J.

Given :

Weight of the crate = 80 N

Distance covered by crate on the slope = 5 m

The angle of inclination on the slope = 30 degrees

Coefficients of friction of slope = 0.05

To Find :

The work done by the gravitational force on the given crate

Solution :

There are multiple forces acting on the crate altogether :

• The Normal force i.e. mg that applies on all bodies
• The force of gravity that acts downwards
• The frictional force that acts against the motion of the crate and involves the use of the coefficient of friction of the surface

Finding the Work done by gravity on the Crate :

The formula for finding the work done in moving a body a distance "d" by applying the force "F" is :

                            $W = F * d\\F = m * a\\W = m *a*d$

Here, the component of gravity along the plane is of sinX towards the motion where X is the angle of inclination of the plane.

Thus, we have :

The force of gravity down the plane  $=mg * sinX$

                                                       $= (80) * sin(30)$

                                                       $= (80)*(1/2)$

                                                       $= 40 N$

The work done by the force of gravity here is $= F_{g} * d$

                                                                            $=40N * 5m$

                                                                            $= 200 J$

Hence, the amount of work done by gravity here is 200J. As it is along the motion, the work done is positive.

To learn more about Work Done, visit

https://brainly.in/question/6103694

#SPJ3