A string 20cm long is stretched to 25cm by a load. What will be it's length when stretched by a load of 100N assuming that the elastic limit is not reached

No way to answer this, without the first load stated.

and it's probably a spring, not a string, anyway.

if it is spring, string, or steel rod is not the point here.

yes

Rumawa

To find the length of the string when stretched by a load of 100N, we need to use Hooke's Law, which states that the extension of a spring is directly proportional to the load applied to it, as long as the elastic limit is not reached.

Hooke's Law can be expressed as follows:

F = k * x

Where:
F is the force (load) applied to the spring
k is the spring constant (a measure of the stiffness of the spring)
x is the extension of the spring

In this case, we have the following information:
Initial length of the string (L₁) = 20cm
Extended length of the string (L₂) = 25cm
Force at L₂ (F₂) = 100N

To find the spring constant (k), we can use the formula:

k = F / x

First, let's calculate the extension of the string (x) when stretched from L₁ to L₂:

x = L₂ - L₁
x = 25cm - 20cm
x = 5cm

Now we can find the value of the spring constant (k):

k = F₂ / x
k = 100N / 5cm
k = 20 N/cm

Finally, we can calculate the length of the string when stretched by a load of 100N:

F = k * x

100N = 20 N/cm * x

Dividing both sides of the equation by 20 N/cm:

5 cm = x

Therefore, the length of the string when stretched by a load of 100N will be 5cm longer than its original length of 20cm, resulting in a final length of 25cm.