Question icon
Grade 10Electric Current

An ideal spring of spring constant 1000 N/m is connected by a pulley as shown in figure and this arrangement is established in the vertical plane. The pulley is ideal and string passing over pulley is massless. In equilibrium of pulley, the masses m1 and m2 are 2 kg and 3 kg respectively. Then the elongation in spring is (Take g = 10 m/s2)

Profile image of Hrishant Goswami
12 Years agoGrade 10
Answers icon

1 Answer

Profile image of Askiitians Tutor Team
ApprovedApproved Tutor Answer1 Year ago

To determine the elongation in the spring when the system is in equilibrium, we need to analyze the forces acting on the masses and how they relate to the spring's properties. Given that the spring constant \( k \) is 1000 N/m, and the masses \( m_1 \) and \( m_2 \) are 2 kg and 3 kg respectively, we can start by calculating the gravitational forces acting on each mass.

Calculating Forces on the Masses

The force due to gravity acting on each mass can be calculated using the formula:

  • Force on \( m_1 \): \( F_1 = m_1 \cdot g = 2 \, \text{kg} \cdot 10 \, \text{m/s}^2 = 20 \, \text{N} \)
  • Force on \( m_2 \): \( F_2 = m_2 \cdot g = 3 \, \text{kg} \cdot 10 \, \text{m/s}^2 = 30 \, \text{N} \)

Understanding the Equilibrium Condition

In equilibrium, the net force acting on the system must be zero. This means that the upward force exerted by the spring must balance the downward forces due to the weights of the two masses. The spring force can be expressed as:

Spring Force: \( F_s = k \cdot x \)

where \( x \) is the elongation of the spring. Since the system is in equilibrium, we can set up the equation:

Net Force: \( F_s = F_2 - F_1 \)

Substituting the values we calculated:

Net Force: \( k \cdot x = 30 \, \text{N} - 20 \, \text{N} \)

This simplifies to:

Spring Force: \( k \cdot x = 10 \, \text{N} \)

Solving for Elongation

Now we can substitute the spring constant into the equation:

1000 N/m \( \cdot x = 10 \, \text{N} \)

To find \( x \), we rearrange the equation:

Elongation: \( x = \frac{10 \, \text{N}}{1000 \, \text{N/m}} = 0.01 \, \text{m} \)

Final Result

The elongation in the spring when the system is in equilibrium is \( 0.01 \, \text{m} \) or \( 1 \, \text{cm} \). This means that the spring stretches by 1 cm due to the difference in weight between the two masses. Understanding this balance of forces is crucial in mechanics, as it illustrates how different components interact in a system.