Answer:
Choice a. 
, assuming that the skating rink is level.
Explanation:
<h3>Net force in the horizontal direction</h3>
There are two horizontal forces acting on the boy:
- The pull of his friend, and
- Frictions.
The boy should be moving in the direction of the pull of his friend. The frictions on this boy should oppose that motion. Therefore, the frictions on the boy would be in the opposite direction of the pull of his friend.
The net force in the horizontal direction should then be the difference between the pull of the friend, and the friction on this boy.
.
<h3>Net force in the vertical direction</h3>
The net force on this boy should be zero in the vertical direction. Consider Newton's Second Law of motion. The net force on an object is proportional to its acceleration. In this question, the net force on this boy in the vertical direction should be proportional to the vertical acceleration of this boy.
However, because (by assumption) the ice rink is level, the boy has no motion in the vertical direction. His vertical acceleration will be zero. As a result, the net force on him should also be zero in the vertical direction.
<h3>Net force</h3>
Therefore, the (combined) net force on this boy would be:
.
You haven't told us what the passing percentage is on the exam,
or what the passing percentage is for the semester, or any of that.
Mass of first car = Initial mass (Mi) = 2 kg
Initial velocity (Vi) = 2 m/s
Mass of both cars together = Final mass (Mf) = 2 + 3 kg = 5 kg
Final Velocity (Vf) = ?
Applying law of conservation of momentum,
Mi x Vi = Mf x Vf
2 x 2 = 5 x Vf
Vf = 4/5 = 0.8 m/s
Answer:
Explanation:
A charge located at a point will experience a zero electrostatic force if the resultant electric field on it due to any other charge(s) is zero.
is located at the origin. The net force on it will only be zero if the resultant electric field intensity due to 
and 
at the origin is equal to zero. Therefore we can perform this solution without necessarily needing the value of .
Let the electric field intensity due to be +
and that due to be -
since the charge is negative. Hence at the origin;
From equation (1) above, we obtain the following;
From Coulomb's law the following relationship holds;
where 
is the distance of from the origin, 
is the distance of from the origin and k is the electrostatic constant.
It therefore means that from equation (2) we can write the following;
k can cancel out from both side of equation (3), so that we finally obtain the following;
Given;
Substituting these values into equation (4); we obtain the following;
