Aflatbed truck is carrying a heavy crate. the coefficient of static friction between the crate and the bed of the truck is 0.75. what is the maximum rate at which the driver can decelerate and still avoid having the crate slide against the cab of the truck? g

We don't want the crate to slip, we are essential to see when the force of deceleration is equal to the force of friction.

Let:

m = mass of the crate 

a = acceleration (in this case deceleration of the truck) 

g = acceleration due to gravity, 9.8 m/s^2 

μ = coefficient of friction, 0.73 

Then 

ma = μmg 

a = μg 

a = 0.75 * 9.8 m/s^2 

a = 7.35 m/s^2 

Therefore, the driver can securely decelerate at about 7.2 m/s^2, any tougher and the crate will probably slide in contradiction of the cab.

c) up is the direction the magnetic force is acting on the charge.

total distance/total time

(85 + 82)/(5+3)

167/8

20 just over