# Physics help, the answer is D but how do you get it?Watch

#1
A wire of diameter 0.80 mm is stretched by a force of 40 N. What is the tensile stress in the wire?
A 0.016 MPa
B 0.05 MPa
C 20MPa
D 80MPa
0
2 months ago
#2
A wire of diameter 0.80 mm is stretched by a force of 40 N. What is the tensile stress in the wire?
A 0.016 MPa
B 0.05 MPa
C 20MPa
D 80MPa
You just need to apply the tensile stress or stress formula

Ensure your conversion of unit is correct (mm to metre).
0
#3
Do you do 0.8^2 * pi * 40 or something else?
0
2 months ago
#4
Do you do 0.8^2 * pi * 40 or something else?
No.

What is the formula for stress?

How do you convert mm to metre?

How compute the cross-sectional area of the wire?
0
2 months ago
#5
First you need to know the formula to work out the tensile stress, which is;

Now find the area as you know the Force (half the diameter) :

Now you have the area just find the stress and divide by 10^6 to get it into MPa
Last edited by Rehman Mallah; 2 months ago
0
#6
Thanks for the help bro
(Original post by Rehman Mallah)
First you need to know the formula to work out the tensile stress, which is;

Now find the area as you know the Force (half the diameter) :

Now you have the area just find the stress and divide by 10^6 to get it into MPa
0
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