Answer :
If the coefficient of friction is 0.8, adding 5 sets of 20 N bricks will result in an 80 N increase in the friction force on the cart. When a surface comes into touch with another, friction acts to prevent motion.
Friction, or more specifically, a reduction in the ratio of output to input, reduces a machine's mechanical advantage. One-fourth of the energy in a car is used to reduce friction force.
the ratio of the normal force pressing two surfaces together to the frictional force preventing motion between the two surfaces. The Greek letter mu () is commonly used to represent it. Using mathematics, is equal to F / N, where F stands for frictional force and N for normal force.
n= 80N/ (coefficient of friction)*20N
n =80/(0.8)*20
n = 5
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