A horizontal force of 50 N is required to pull an 8 kg block of aluminum at a uniform
velocity across a horizontal wooden desk. What is the coefficient of kinetic friction?
To find the coefficient of kinetic friction, we need to use the equation:
Frictional force = coefficient of kinetic friction × normal force
The normal force is the force exerted by the wooden desk on the block, which is equal to the weight of the block. The weight can be calculated using the equation:
Weight = mass × gravitational acceleration
Given that the mass of the block is 8 kg and the acceleration due to gravity is approximately 9.8 m/s^2, we can find the weight:
Weight = 8 kg × 9.8 m/s^2 = 78.4 N
Since the block is moving at a uniform velocity, the frictional force is equal to the applied horizontal force of 50 N:
Frictional force = 50 N
Now we can rearrange the equation to solve for the coefficient of kinetic friction:
coefficient of kinetic friction = frictional force / normal force
coefficient of kinetic friction = 50 N / 78.4 N
coefficient of kinetic friction ≈ 0.64
So, the coefficient of kinetic friction between the block of aluminum and the wooden desk is approximately 0.64.