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Grade 12Electrostatics

et mass of both the charges is m and charge on both the charges is q

take a sphere which is at height div two forces act on it

force of gravitation in downword direction and electrostatic force in downward direction hence net downward direction is qe+mg/m hence accelaration is qe/m+g hence

div=1/2(g+qe/m)t^2

let t is time taken by small sphere in travelling distance

l=vt , t=l/v

let x is distance travelled by second sphere

forces acting on it

force of gravitation downward and electrostatic force upwards hence net acceleration in downward direction is( g-qe/m)

X=1/2(g-qe/m)t^2

height at this instant is h2-x

x=gl^2/v^2-div

hence height is h2-(gl^2/v^2)

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8 Years agoGrade 12
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1 Answer

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ApprovedApproved Tutor Answer1 Year ago

To analyze the motion of two charged spheres under the influence of gravitational and electrostatic forces, we can break down the problem step by step. Let's consider the forces acting on each sphere and how they affect their respective motions.

Understanding the Forces

We have two spheres, each with mass m and charge q. The first sphere is at a height h1 and experiences two forces:

  • The gravitational force acting downward, which is mg.
  • The electrostatic force acting downward, which is qe (assuming the charge is positive and the force is attractive).

The net force acting on the first sphere can be expressed as:

F_net = qe + mg

This leads to a net acceleration a1 given by:

a1 = (qe + mg) / m = (qe/m) + g

Calculating the Distance Travelled

Using the kinematic equation for distance, we can express the height h1 in terms of time t:

h1 = (1/2)(a1)t^2 = (1/2)((qe/m) + g)t^2

Now, if we denote the distance travelled by the sphere as l, we can relate time to distance:

t = l/v

Analyzing the Second Sphere

Now, let’s consider the second sphere, which is also affected by gravitational and electrostatic forces. The forces acting on it are:

  • The gravitational force acting downward, mg.
  • The electrostatic force acting upward, qe.

The net acceleration a2 for the second sphere can be expressed as:

a2 = (g - qe/m)

Distance Travelled by the Second Sphere

Using the same kinematic equation, we can express the distance X travelled by the second sphere:

X = (1/2)(g - qe/m)t^2

At this point, the height of the second sphere can be expressed as:

h2 = h - X

Substituting for X, we get:

h2 = h - (1/2)(g - qe/m)t^2

Final Relationships

Now, if we substitute the expression for X into the height equation, we can find the relationship between the heights:

X = (gl^2/v^2) - h1

Thus, the height at this instant can be expressed as:

h2 = h - (gl^2/v^2)

Summary of Findings

In summary, we have derived the equations governing the motion of two charged spheres under the influence of gravitational and electrostatic forces. The first sphere accelerates downward due to the combined effect of gravity and electrostatic attraction, while the second sphere experiences a net downward acceleration due to gravity and electrostatic repulsion. By applying kinematic equations, we can relate the distances travelled and the heights of both spheres at any given time.