A Level Physics Practice Exam

What happens to the spring constant when two springs are used in parallel?

1. The spring constant is halved

2. The spring constant is doubled

3. There is no change in the spring constant

4. The spring constant increases by a factor of three

The correct answer is: The spring constant is doubled

When two springs are connected in parallel, the effective spring constant of the system increases. This is because each spring will share the load when a force is applied, leading to a combined effect that results in a greater resistance to stretching or compressing compared to a single spring alone. The formula for calculating the effective spring constant \( k_{\text{eff}} \) of two springs in parallel is given by: \[ k_{\text{eff}} = k_1 + k_2 \] where \( k_1 \) and \( k_2 \) are the spring constants of the individual springs. If both springs have the same spring constant \( k \), then: \[ k_{\text{eff}} = k + k = 2k \] This demonstrates that the effective spring constant is doubled when two identical springs are used in parallel. Consequently, the more springs that are added in parallel, the higher the effective spring constant becomes, as each additional spring contributes its own spring constant to the total. Thus, the results align with the observation that the spring constant is indeed doubled when two springs are in parallel.