Answer:
Step-by-step explanation:
The frictional force between the sled and block (stuck together) and the flat ground can be calculated using the formula:
friction = coefficient of friction * normal force
The normal force is the force exerted on an object perpendicular to the surface it is in contact with, and it can be calculated by using the weight of the object (mg). In this case, the weight of the sled and block (stuck together) is 12 kg + 8 kg = 20 kg. So, the normal force is 20 kg * 9.8 m/s^2 = 196 N.
Using the coefficient of friction provided (µ = .75), we can calculate the frictional force as:
friction = .75 * 196 N = 147 N.
So, the frictional force between the sled and block (stuck together) and the flat ground is 147 N.