Answer:
trying to push a rock that never moves
Explanation:
For a parallel circuit with two resistors, the total resistance is calculated from the expression:
1/R = 1/R1 + 1/R2
We are given the total resistance, R, which is 20 ohms and R2 which is 75 ohms. We calculate R1 as follows:
1/20 = 1/R1 + 1/75
1/R1 = 11/300
R1 = 27.27 ohms
Answer:
The acceleration is a = 2.75 [m/s^2]
Explanation:
In order to solve this problem we must use kinematics equations.

where:
Vf = final velocity = 13 [m/s]
Vi = initial velocity = 2 [m/s]
a = acceleration [m/s^2]
t = time = 4 [s]
Now replacing:
13 = 2 + (4*a)
(13 - 2) = 4*a
a = 2.75 [m/s^2]
In order to draw the free body diagram, first let's calculate the friction force acting on the crate:

Since the friction force is greater than the force applied, the crate will not move, and the friction force will be equal to the force applied.
The weight force is equal to 40 * 9.8 = 392 N.
So, drawing the diagram, we have: