Answer: Option (c) is the correct answer.
Explanation:
It is known that the expression for potential energy related to charges and distance between their separation is as follows.
where, 
and 
are two charges
r = distance of separation between the charges
k = electrostatic constant
So, when both the charges are carry the same charge and r is small then the value of potential energy will be positive in nature.
Whereas if the distance of separation between the charges is infinitely large then the potential energy calculated will be zero everywhere.
Thus, we can conclude that the statement one object is negatively charged and the other one is positively charged, is incorrect.
Answer:
69.66 rad/s
Explanation:
Suppose the handle of the crank is L = 1 m long. We can calculate the torque:
T = F*L = 258*1 = 258 Nm
Then the angular momentum is given to the handle within 0.27 seconds is
rad/s
Walking at a speed of 2.1 m/s, in the first 2 s John would have walked
(2.1 m/s) (2 s) = 4.2 m
Take this point in time to be the starting point. Then John's distance from the starting line at time <em>t</em> after the first 2 s is
<em>J(t)</em> = 4.2 m + (2.1 m/s) <em>t</em>
while Ryan's position is
<em>R(t)</em> = 100 m - (1.8 m/s) <em>t</em>
where Ryan's velocity is negative because he is moving in the opposite direction.
(b) Solve for the time when they meet. This happens when <em>J(t)</em> = <em>R(t)</em> :
4.2 m + (2.1 m/s) <em>t</em> = 100 m - (1.8 m/s) <em>t</em>
(2.1 m/s) <em>t</em> + (1.8 m/s) <em>t</em> = 100 m - 4.2 m
(3.9 m/s) <em>t</em> = 95.8 m
<em>t</em> = (95.8 m) / (3.9 m/s) ≈ 24.6 s
(a) Evaluate either <em>J(t)</em> or <em>R(t)</em> at the time from part (b).
<em>J</em> (24.6 s) = 4.2 m + (2.1 m/s) (24.6 s) ≈ 55.8 m
