A force of 5 N compresses two identical springs in series by 10 cm. What will be the total distance that the same springs in parallel are compressed?

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Your interviewer will likely ask you situation- and knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. In this case, springs can be generally described by Hooke's law (F = kx), which states that the amount of distance extended or compressed in a spring is proportional to the force applied by a spring constant (k). This question can be solved by using the effective spring constant, which is the sum of the individual spring constants in series, and the sum of their reciprocals in parallel. The springs are identical and thus have the same spring constant, which simplifies to k_eq = 2*k in series and k_eq = 2/k in parallel. We observe that the springs in parallel would have an effective spring constant that is half of the effective spring constant in series. Using Hooke's law, we can conclude that they would be compressed by half the distance.

"The springs in parallel would be compressed by half of the distance, or 5 cm. This can be determined by using Hooke's law as well as the relationship between the effective spring constant in series and in parallel. The effective spring constant in series would be the force (5 Newtons) divided by the compression distance (0.05 meters), resulting in 100 Newtons per meter. Because the springs are identical, their effective spring constant in parallel is exactly half of that in series. Therefore, the spring constant in parallel would be 50 Newtons per meter, which would compress the springs by 5 centimeters in response to a 5 Newton force."

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How to Answer: A force of 5 N compresses two identical springs in series by 10 cm. What will be the total distance that the same springs in parallel are compressed?

Advice and answer examples written specifically for a Mechanical Engineer job interview.

37. A force of 5 N compresses two identical springs in series by 10 cm. What will be the total distance that the same springs in parallel are compressed?

How to Answer

Your interviewer will likely ask you situation- and knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. In this case, springs can be generally described by Hooke's law (F = kx), which states that the amount of distance extended or compressed in a spring is proportional to the force applied by a spring constant (k). This question can be solved by using the effective spring constant, which is the sum of the individual spring constants in series, and the sum of their reciprocals in parallel. The springs are identical and thus have the same spring constant, which simplifies to k_eq = 2*k in series and k_eq = 2/k in parallel. We observe that the springs in parallel would have an effective spring constant that is half of the effective spring constant in series. Using Hooke's law, we can conclude that they would be compressed by half the distance.

Written by Jason Toby on October 12th, 2020

Answer Example

"The springs in parallel would be compressed by half of the distance, or 5 cm. This can be determined by using Hooke's law as well as the relationship between the effective spring constant in series and in parallel. The effective spring constant in series would be the force (5 Newtons) divided by the compression distance (0.05 meters), resulting in 100 Newtons per meter. Because the springs are identical, their effective spring constant in parallel is exactly half of that in series. Therefore, the spring constant in parallel would be 50 Newtons per meter, which would compress the springs by 5 centimeters in response to a 5 Newton force."

Written by Jason Toby on October 12th, 2020

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