1-4 Spring constant

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Spring constant (p. 14)

Bluetooth 

- ON

- VPN off

Stationary

- Writingbook

- Pen and pencil

- Calculator

- iPad

Report

- NO

Lessonup

- YES

Schoolbags in

the cupboard

Phones in the phonebag

Lesson goal:

Calcualte the spring constant, force or extention of a spring using the formula.

Spring constant formula

C=​x​​F​​

C = spring constant

          (N/cm)

F = force 

            (N)

x = extention of spring

       (cm of mm of m)

What is the unit of C in the formula?

1. N
2. cm
3. N/cm
4. cm/N

What is the unit of F in the formula?

1. N
2. cm
3. N/cm
4. cm/N

Example 1

A spring is 23,5 cm long if nothing hangs on it and 33,1 cm long if a mass of 350 grams hangs on it. Calculate the spring constant.(6p)

GIven     x = 33.1-23,5 = 9,6 cm

                      m = 350 g = 0,35 kg

Asked      C = ?

Calculation  F = mg = 0,35 x 9,8 = 3,43 N

C=​x​​F​​

=​9,6​​3,43​​

= 0,36 N/cm

Example 2

The zero position of a spring is 15 cm. If the spring constant is 42 N/m and a force of 6N acts on the spring, what is the length of the spring?

Given    (zero position) = 15 cm

                     C = 42 N/m

                     F = 6N

Asked   length of the spring (15 + x)

Uitwerking   

x=​C​​F​​

=​42​​6​​

= 0,14m = 14 cm

So x = 15 + 14 = 29cm

Your turn

Daan does a practical with a spring (C = 35 N/m). First he measures the length of the spring if nothing hangs on it: 27cm. thereafter he hangs a block of 300 gram on the spring. Calculate the total length of the spring. 

Given   C = 35 N/m

                      zero position = 27 cm

                      m = 300 g = 0,3 kg

Asked    length of spring (27 + x)

Calculation   F =mg = (0,3)(9,8) = 2,94 N

x=​c​​F​​

=​35​​2,94​​

= 0,084 m = 8,4 cm

Calculation = 27 + 8,4 = 35,4 cm

What must you remember when writing a formula...

1. Use the original formula
2. Write that what you want to calculate left of the =

Do question 18

Do question 19

Homework

Do the skillstrainer of 1.2 in the digital method

Answer questions 14 and 17 in the digital method

What have you
learnt today?

Conclusion

C=​u​​F​​

We can calculate this with m x g

calculate with end position - zero position