# Springs

## Mechanical Aptitude Test - Springs

A Spring is a piece of metal that can be extended or compressed by an external force which then returns to

There are many different types of spring including, spiral coil, leaf

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**Springs**

Definition

#### Below you will find some mechanical aptitude test spring questions and answers:

##### Springs - Example 1

The figure shows a mass of 5 kg attached to a rope and a spring, we know that the tension in the rope is 10 N, the spring must be:

A) Extended

B) Compressed

C) Neutral

Answer: B

The weight of the mass is about 50 N, so a force must be acting upwards to support the weight a little bit because the tension in the rope is less than the weight, which means the spring must be compressed.

##### Springs - Example 2

What is the force needed to move the mass 2 inches to the right as shown in this figure? Neglect friction.

A) 24 pounds

B) 34 pounds

C) 10 pounds

Answer: A

The force of the spring is equal to the constant of the spring times the displacement, which equals to 12 * 2 = 24 pounds

##### Springs - Example 3

By putting the 2 kg mass first, the spring displaces a distance of 5 mm, then we replace that spring with another one and add another 3 kg mass, we see that it displaces the same distance, the second spring is:

A) Double the first spring's stiffness

B) More than double

C) less than double

Answer: C

The second spring endured 1.5 times the weight with the same displacement, so it's 1.5 times as stiff as the first.

##### Springs - Example 4

The 3 kg collar is released from rest at height (h) from the spring, we see that it deforms a distance (s) on impact, we then replace the spring and do the experiment again, this time, to see the new spring deform a distance (2s), which of the springs is stiffer ?

A) The first spring.

B) The second spring

C) Stiffness doesn't depend on deformation only.

Answer: A

The potential energy consumed by the spring is equal to 0.5 * stiffness * displacement2

As the first spring deformed slightly less, it must have

##### Springs - Example 5

Which configuration do you think has more overall stiffness?

A) The right one.

B) The left one.

C) Both have the same stiffness.

Answer: B

Suppose we displace each mass to the left a distance (s), now on the left figure, each spring will deform a distance (s) hence, will act by a force (k*s), so a total force of (2ks).

Now the right figure, each spring will deform with (0.5 * s) and will act with a force of (0.5ks) and only one spring is attached to the mass, so a total force of (0.5ks).

Because the left system has more force for the same displacement, it has more stiffness.