When too many people stand on a bridge it collapses, why?
A.
Due to increase in stress
B.
Due to overweight
C.
Due to improper construction
D.
Due to friction
Answer: Option A
Explanation:
Stress is the force per unit area experienced by the body and strength is the ability to withstand the stress. When stress becomes greater than strength, accidents happen.
For a constant force, a rope breaks due to stress. Which of the following is useful to reduce the stress?
A.
Increase the length of the rope
B.
Apply small force
C.
Increase the cross sectional area of the rope
D.
Use a different material of rope
Answer: Option C
Explanation:
Stress = Force/Area For a constant force, if the area is small, stress is large. If the area is large, stress is small. Therefore by increasing the cross sectional area stress can be reduced considerably.
When a rope is pulled on either side, what is the stress acting on it?
A.
Compressive stress
B.
Tensile stress
C.
Tensile stress
D.
Tangential stress
Answer: Option B
Explanation:
A tensile stress occurs when something is being pulled. A rope experiences tensile stress because it is flexible. In other words, a rope cannot be pushed.
What happens when the stress applied to the body is increased beyond the maximum value and is removed after some time?
A.
The body will come back to its original position
B.
The body will oppose the stress
C.
The body becomes hot
D.
The body cannot return to its original position
Answer: Option D
Explanation:
When the applied stress exceeds the maximum value the body does not regain its original position completely after removing external forces. It is said to have reached its elastic limit.
