Answer:
Explanation:
The computation of the weight of the paper in newtons is shown below:
On the paper, the induced charge is of the same magnitude as on the initial charges and in sign opposite.
Therefore the paper charge is
Now the distance from the charge is
Now, to raise the paper, the weight of the paper acting downwards needs to be managed by the electrostatic force of attraction between both the paper and the charge, i.e.
Answer:
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
Explanation:
From the law of equilibrium, ΣF = 0 and ΣM = 0.
Let R be the reaction at the knife edge. Since the weight of the rod and zinc load act downward, and we take downward position as negative
-32 N - 2 N + R = 0
-34 N = -R
R = 34 N
Also, let us assume the knife-edge is x cm from the zero mark. Taking moments about the weight and assuming the knife-edge is right of the weight of the rod. Taking clockwise moments as positive and anti-clockwise moments as negative,
-(45 - 25)2 + (x - 45)R = 0
-(20)2 + (x - 45)34 = 0
-40 = -(x - 45)34
x - 45 = 40/34
x - 45 = 1.18
x = 45 + 1.18
x = 46.18 cm
x ≅ 46.2 cm
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
Answer:
B) Kinetic energy increases, potential energy decreases
Explanation:
In a given system, when a body is at rest, v =0m/s, the kinetic energy is at zero while the potential energy is at maximum. However, when a body is in motion with a velocity = v, the potential energy is at zero while the kinetic energy is at maximum.
Before this happen, the a body at rest (P.E = max) is set on motion, the kinetic energy gradually increases till it converts all the potential energy in the system to kinetic energy and then reverses back when the body goes to rest again.
In this case, before the batter hits the ball, the kinetic energy was at zero while the potential energy was at maximum. However, when he hits the ball and sets it into motion with a velocity V, the potential energy converts to kinetic energy and moves the ball with that energy till it has expanded it and comes to rest.
Potential Energy → Kinetic Energy → Potential Energy.
That's how the system keeps changing.
