Ends of a light string are tied to two hooks A&B in a ceiling which are 100cm apart horizontally so that the length of the string between the hooks is 140cm. A 650g mass is then attached by a second length of string t a point C on the first 80cm from A and hangs freely. Find by drawing the tension in the portion AC & BC of the string.

Relevance

Draw a square.

Label the top edge as 100, the left corner A and the right corner B.

Mark a point C a little to the rightt of the center of the square.

Draw a line from A to C

Draw a line from B to C

Label AC as 80

Label BC as 60

This ABC triangle is 100 by 80 by 60

Now draw an arrow straight down from C label it 650

Make the arrow 6.5 centimeters long to make things simple.

Now continue line AC with your ruler and pencil

Do the same with line BC

Starting at the arrow tip, use your ruler to draw a line parallel by eye to line AC

Repeat for BC.

Measure the two new lines in centimeters. These are your tension forces, remembering that 6.5 cm is the scale for 650 grams.