I’m pretty sure the answer would be D, sorry if it’s not correct!
Incomplete question. Missing part:
"it took him 10 seconds to move the couch. What was his power?"
Answer:
50 W
Explanation:
The power developed is given by:

where
W is the work done
t is the time taken
In this problem,
W = 500 J
t = 10.0 s
Substituting into the equation, we find

Answer:
v_avg = 37 km/h
Explanation:
To find the average velocity in the complete trajectory you use the following formula:
( 1 )
v1: velocity in the first part of the trajectory = 70 km/h
v2: velocity in the second part of the trajectory = ?
You calculate v2 by using the following equation for a motion with constant velocity:

you replace the values of v1 and v2 in (1) and you obtain:

hence, the average velocity is 37 km/h
Answer:
FC vector representation

Magnitude of FC

Vector direction FC
degrees: angle that forms FC with the horizontal
Explanation:
Conceptual analysis
Because the particle C is close to two other electrically charged particles, it will experience two electrical forces and the solution of the problem is of a vector nature.
The directions of the individual forces exerted by qA and qB on qC are shown in the attached figure; The force (FAC) of qA over qC is repulsive because they have equal signs and the force (FBC) of qB over qC is attractive because they have opposite signs.
The FAC force is up in the positive direction and the FBC force forms an α angle with respect to the x axis.
degrees
To calculate the magnitudes of the forces we apply Coulomb's law:
Equation (1): Magnitude of the electric force of the charge qA over the charge qC
Equation (2)
: Magnitude of the electric force of the charge qB over the charge qC
Known data





Problem development
In the equations (1) and (2) to calculate FAC Y FBC:


Components of the FBC force at x and y:


Components of the resulting force acting on qC:


FC vector representation

Magnitude of FC

Vector direction FC
degrees: angle that forms FC with the horizontal