physics a level question WAVES :) (another one yeah soz lol)

yeah sorry i have another question :smile:

im stuck on 3a. I got the wrong answer.

what i did

w=mg
40=mg
m= 4.077

therefore the mass per unit length is 4.077/0.8 = 5.096 which gives the wrong answers

Untitled document (60).pdf201.9KB

Reply 1

Stonebridge

Original post by vix.xvi

yeah sorry i have another question :smile:

im stuck on 3a. I got the wrong answer.

what i did

w=mg
40=mg
m= 4.077

therefore the mass per unit length is 4.077/0.8 = 5.096 which gives the wrong answers

For some reason you have used 40 as the weight of the wire, it seems.
The value of 40 given is the tension in the wire.
There is then a formula which relates the tension to the mass per unit length.

Reply 2

username3477548

Original post by Stonebridge

For some reason you have used 40 as the weight of the wire, it seems.
The value of 40 given is the tension in the wire.
There is then a formula which relates the tension to the mass per unit length.

ahh ok thanks :smile:

but itsnt the tension in the wire the same as the force of the weight on it if that makes sense?

Reply 3

Stonebridge

Original post by vix.xvi

ahh ok thanks :smile:

but itsnt the tension in the wire the same as the force of the weight on it if that makes sense?

Definitely not. The weight of the wire is a result of its mass. The tension in the wire is a result of how tight you pull out its ends.
The mass of the wire is constant. The tension depends on how hard you stretch it.