Three identical charged balls each of charge \(2\) \(C\) are suspended from a common point \(P\) by silk threads of \(2\) \(m\) each (as shown in figure). They form an equilateral triangle of side \(1\) \(m\). The ratio of net force on a charged ball to the force between any two charged balls will be:
- \(1:1\)
- \(1:4\)
- \(\sqrt3:2\)
- \(\sqrt3:1\)
The Correct Option is D
Solution and Explanation
Force between any two charged balls will be:
\(F_{net}\) on charge \(3\),
\(F_1=\frac{\sqrt3kq^2}{1 ^2}\)
Force between any \(2\) charges
\(F_2=\frac{kq^2}{1 ^2}\)
So,
\(\frac{F_1}{F_2}=\sqrt3\)
Hence, the correct option is (D): \(\sqrt 3 : 1\)
Top Questions on Forces
- In which cases does a charged particle not experience a force in a magnetic field?
- Two bodies of masses \( M \) and \( 4M \) initially at rest, start moving towards each other due to their mutual attraction. The velocity of their centre of mass when the first body attains a velocity \( v_0 \) is
- A motor can pump 7560 kg of water per hour from a well of depth 100 m. If the efficiency of the pump is 70%, then the power of the pump is:
- A body of mass \( M \) is moving with a uniform speed \( v \) on a frictionless horizontal surface under the influence of two forces \( F_1 \) and \( F_2 \) as shown in the figure. The net power of the system is:
- A crane of efficiency 80% is used to lift 8000 kg of coal from a mine of depth 108 m. If the time taken by the crane to lift the coal is one hour, then the power of the crane (in kW) is (Acceleration due to gravity \( = 10 \, \text{m s}^{-2} \))
Questions Asked in JEE Main exam
A bob of mass \(m\) is suspended at a point \(O\) by a light string of length \(l\) and left to perform vertical motion (circular) as shown in the figure. Initially, by applying horizontal velocity \(v_0\) at the point ‘A’, the string becomes slack when the bob reaches at the point ‘D’. The ratio of the kinetic energy of the bob at the points B and C is:
- JEE Main - 2025
- Kinetic Energy
- The number of different 5 digit numbers greater than 50000 that can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7, such that the sum of their first and last digits should not be more than 8, is:
- JEE Main - 2025
- permutations and combinations
- A bar magnet has total length \( 2l = 20 \) units and the field point \( P \) is at a distance \( d = 10 \) units from the centre of the magnet. If the relative uncertainty of length measurement is 1%, then the uncertainty of the magnetic field at point P is:
- JEE Main - 2025
- Magnetic Field
- A force of 49 N acts tangentially at the highest point of a sphere (solid of mass 20 kg) kept on a rough horizontal plane. If the sphere rolls without slipping, then the acceleration of the center of the sphere is:
- JEE Main - 2025
- Quantum Mechanics
Let $ P_n = \alpha^n + \beta^n $, $ n \in \mathbb{N} $. If $ P_{10} = 123,\ P_9 = 76,\ P_8 = 47 $ and $ P_1 = 1 $, then the quadratic equation having roots $ \alpha $ and $ \frac{1}{\beta} $ is:
- JEE Main - 2025
- Relations and functions
Concepts Used:
Forces
A force is a physical influence that can cause an object to change its motion or shape. Forces can be classified into two broad categories: contact forces and non-contact forces.
Contact forces arise from direct physical contact between two objects. Examples of contact forces include friction, tension, normal force, and air resistance.
Non-contact forces, also known as field forces, act at a distance and do not involve physical contact between objects. Examples of non-contact forces include gravitational force, electric force, and magnetic force.
Forces can be described in terms of their magnitude, direction, and point of application. The magnitude of a force is typically measured in units of newtons (N), and the direction is specified using vectors.
The effects of forces can be described using Newton's laws of motion. Newton's first law states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity unless acted upon by an unbalanced force. Newton's second law relates the force applied to an object to its resulting acceleration, and Newton's third law states that for every action, there is an equal and opposite reaction.
Forces play a fundamental role in many branches of physics, including mechanics, electromagnetism, and thermodynamics. They are essential to understanding the behavior of physical systems and are important in applications such as engineering, medicine, and space exploration.