The maximum amount of pulling force a truck can apply when driving on concrete is 10,560 N. If the coefficient of static friction between a trailer and

concrete is 0.8, what is the heaviest that the trailer can be and still be pulled

by the truck?

Explanation:

Let the weight of the truck be W . reaction force R = W

Maximum frictional force = μ R

= .8 x W

So for movement of truck

Pulling force = frictional force

10560 = .8W

W = 13200 N

weight of heaviest truck required = 13200 N .

snell's law

refractve index = sin incidence / sin refraction

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.