The coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.
Explanation:
Coefficient of static friction is defined as the proportionality constant for the frictional force between the crate and floor for starting the motion of crate and normal force acting on the crate. As the normal force of the crate is equal to the influence of acceleration due to gravity acting on the mass of the crate, the frictional force for static friction coefficient will be the force applied to move the crate.
Thus, 
Since, the static friction force is 70 N, the normal force is equal to 
So normal force is 196 N and static force is 70 N, and the ratio of static friction force to the normal force will give the coefficient of static friction.

Similarly, the coefficient of kinetic friction can be determined from the ratio of kinetic friction force to normal force. Here the kinetic friction force will be equal to the force applied on the crate to keep it moving.

Thus, the coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.
Longshore current brings about the transportation of sediments on the beach. Since waves usually approach the shore are an angle, the beach sand are carried up or down depending on the direction of the waves resulting in beach drift, that is, the net movement of the beach sand.
To solve this problem we will apply the linear motion kinematic equations, specifically the concept of acceleration as a function of speed and time, as well as Newton's second law.
PART A) Acceleration can be described as changing the speed in a period of time therefore,

Force is the proportional change between mass and acceleration therefore


PART B) We will apply the same concept given but now we will change the time to 21s therefore:

Now the force


Every magnet has at least one “North” and one “South” pole where its magnetic forces leave the magnet and enter its surroundings. It is commonly thought that the magnetic forces leave one pole and enter the other pole. Therefore, The magnetic forces are <span>concentrating the forces between those poles and making the attraction/repulsion stronger. Hope this helps! :)
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