A 2.30 102 N force is pulling an 80.0 kg refrigerator across a horizontal surface. The force acts at an angle of 21.0° above the surface. The coefficient of kinetic friction is 0.200, and the refrigerator moves a distance of 7.00 m.
(a) Find the work done by the pulling force.
(b) Find the work done by the kinetic frictional force.
work done= force.distance where the dot is the cosine of the angle between.
= 2.3E2*7 * cosine 21
work done by friction:
= forcefriction*distance=mu(fn)*distance
where fnormal= mg-2.3E2Sin21
(a) 2.30*10^2*cos21*7.00 m = ___ J
(b) 80.0*g*(0.200)*7.00 = (-) ____ J
The friction force actually does negative work.
The answer is wrong. What did u get?
My part b is wrong because I neglected the upward force provided by the rope, which reduces friction. Use BobPursely's equation
you use the mg-(2.3E2*cos21)for fnormal...bobpursley you really should check your work before...
To find the work done by the pulling force and the work done by the kinetic frictional force, we need to first understand the concept of work and how it is calculated.
Work is defined as the product of the force applied on an object and the displacement of the object in the direction of the force. Mathematically, work (W) can be calculated using the formula:
W = F * d * cosθ
where F is the applied force, d is the displacement, and θ is the angle between the force and the direction of displacement.
Now let's calculate the work done by the pulling force and the work done by the kinetic frictional force:
(a) Work done by the pulling force:
The given force is 2.30 * 10^2 N, and the displacement is 7.00 m. The angle between the force and displacement is 21.0°. Using the formula for work, we have:
W = (2.30 * 10^2 N) * (7.00 m) * cos(21.0°)
To calculate cos(21.0°), we need to convert the angle to radians. 21.0° * (π/180°) = 0.366519 radians. Now we can calculate the work:
W = (2.30 * 10^2 N) * (7.00 m) * cos(0.366519)
(b) Work done by the kinetic frictional force:
The coefficient of kinetic friction is given as 0.200. To find the frictional force, we need to multiply the coefficient by the normal force. The normal force can be calculated using the formula:
Normal force (N) = mass * gravity
where the mass is given as 80.0 kg and the acceleration due to gravity is approximately 9.8 m/s^2. Therefore, the normal force is:
N = (80.0 kg) * (9.8 m/s^2)
Now, we can calculate the frictional force:
Frictional force = coefficient of kinetic friction * normal force
Frictional force = (0.200) * ((80.0 kg) * (9.8 m/s^2))
To find the work done by the frictional force, we multiply the frictional force by the displacement:
W = (Frictional force) * (displacement)
W = [(0.200) * ((80.0 kg) * (9.8 m/s^2))] * (7.00 m)
By substituting the known values into the equations, you can calculate the work done by the pulling force and the work done by the kinetic frictional force.