Physics - An easy AS mechanics question.

I am having troble with the second part of this question. Its been a while since I've done Mechanics so my memory isn't so good

The diagram shows a picture supported by two wires. Th wires exert forces at A and B as shown.

'Ican't show you the diagram but just imagine a picture been held up on a wall with the strings making a triangle shape due to a pin in the wall.

The tension in the strings in 5N. The strings are both at an angle of 37 degrees.

a) Resolve the forve acting at B to calculate its vertical and horizontal components

b) Calculate the wright of the picture assuming it hangs freely

I can do part a which is just:

5cos 37=4.0
5sin37=3.0

but not b.

This is the information I have been given. Any help would be appreciated.

Reply 1

Hoofbeat

14

Bebop

I am having troble with the second part of this question. Its been a while since I've done Mechanics so my memory isn't so good

The diagram shows a picture supported by two wires. Th wires exert forces at A and B as shown.

'Ican't show you the diagram but just imagine a picture been held up on a wall with the strings making a triangle shape due to a pin in the wall.

The tension in the strings in 5N. The strings are both at an angle of 37 degrees.

a) Resolve the forve acting at B to calculate its vertical and horizontal components

b) Calculate the wright of the picture assuming it hangs freely

I can do part a which is just:

5cos 37=4.0
5sin37=3.0

but not b.

This is the information I have been given. Any help would be appreciated.

The vertical components of each of the wires must equal the weight due to the picture frame as the system is in equilibrium, ie. not moving

2(5sin37) = mg

solve this to get mg (or weight) = 6.018.... = 6.02N (3sf) :smile:

Reply 2

john !!

14

Some ambiguous descriptions, I'm assuming the angle given is to the horizontal, and that the picture is in equilibrium.

Vertical component of tension in strings:

2 (5 sin 37) = 6.01815N

This can be equated to the picture's weight

W = 6.01815N

Using the equation W = mg

m = 6.01815/9.8 = 0.614kg