A 74 kg box rests on a level surface. The coefficient of static friction, µS = 1.1 and the coefficient of kinetic friction, µK = 0.7 . What is the magnitude of Friction on the box from the surface?
Wb = m * g = 74kg * 9.8N/kg = 725.2 N. =
Weight of box.
Fs = u * Wb = 1.1 * 725.2 = 797.7 N. =
Force of static friction.
To find the magnitude of the friction on the box from the surface, we need to consider whether the box is at rest or in motion.
1. If the box is at rest:
When the box is at rest, the static friction comes into play. The formula for static friction is given by:
Fstatic = µS * N
where Fstatic is the force of static friction, µS is the coefficient of static friction, and N is the normal force.
The normal force is equal to the weight of the box, which is the product of the mass (m) and the acceleration due to gravity (g):
N = m * g
Plugging in the given values, we have:
N = 74 kg * 9.8 m/s^2 = 725.2 N
Now, substitute the values of µS and N into the formula for static friction:
Fstatic = 1.1 * 725.2 N = 797.72 N
Therefore, the magnitude of the friction on the box from the surface when it is at rest is 797.72 N.
2. If the box is in motion:
When the box is in motion, the kinetic friction comes into play. The formula for kinetic friction is given by:
Fkinetic = µK * N
Using the same values for N as calculated above, we can substitute the values of µK and N into the formula for kinetic friction:
Fkinetic = 0.7 * 725.2 N = 507.64 N
Therefore, the magnitude of the friction on the box from the surface when it is in motion is 507.64 N.