Question:
A body of mass $1 kg$ collides head on elastically with a stationary body of mass $3 kg$ After collision, the smaller body reverses its direction of motion and moves with a speed of $2 m / s$ The initial speed of the smaller body before collision is ___ $ms ^{-1}$
A body of mass $1 kg$ collides head on elastically with a stationary body of mass $3 kg$ After collision, the smaller body reverses its direction of motion and moves with a speed of $2 m / s$ The initial speed of the smaller body before collision is ___ $ms ^{-1}$
Updated On: Mar 19, 2025
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Correct Answer: 4
Approach Solution - 1
The correct answer is 4.
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Approach Solution -2
By applying the principle of conservation of momentum and considering the reversal of direction and speed after the collision, we use the equation of motion:
\[
m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2
\]
Using the given masses and velocities, we solve for \( u_1 \), which is found to be \( 4 \, \text{m/s} \) in the opposite direction.
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Concepts Used:
Work, Energy and Power
Work:
- Work is correlated to force and the displacement over which it acts. When an object is replaced parallel to the force's line of action, it is thought to be doing work. It is a force-driven action that includes movement in the force's direction.
- The work done by the force is described to be the product of the elements of the force in the direction of the displacement and the magnitude of this displacement.
Energy:
- A body's energy is its potential to do tasks. Anything that has the capability to work is said to have energy. The unit of energy is the same as the unit of work, i.e., the Joule.
- There are two types of mechanical energy such as; Kinetic and potential energy.
Read More: Work and Energy
Power:
- Power is the rate at which energy is transferred, conveyed, or converted or the rate of doing work. Technologically, it is the amount of work done per unit of time. The SI unit of power is Watt (W) which is joules per second (J/s). Sometimes the power of motor vehicles and other machines is demonstrated in terms of Horsepower (hp), which is roughly equal to 745.7 watts.
- Power is a scalar quantity, which gives us a quantity or amount of energy consumed per unit of time but with no manifestation of direction.