The tension in a spring of natural length l0 is first increased from zero to T1, causing the length to increase to l1. The tension is then reduced to T2, causing the length to decrease to l2 (as shown).
Which area of the graph represents the work done by the spring during this reduction in length?
A MLP
B MNQP
C MNSR
D MPLU
A simple crane consists of a rigid vertical pillar supporting a horizontal beam. A weight W is lifted by a rope at the end of the beam.
What are the forces at points X, Y and Z due to the weight W?
A force at X = tension; force at Y = compression; force at Z = tension.
B force at X = tension; force at Y = tension; force at Z = compression.
C force at X = compression; force at Y = tension ; force at Z = compression.
D force at X = compression; force at Y = compression; force at Z = compression.
A sample of metal is subjected to a force which increases to a maximum value and then decreases back to zero. A force-extension graph for the sample is shown at the left. When the sample contracts it follows the same force-extension curve as when it was being stretched.
What is the behaviour of the metal between X and Y?
A both elastic and plastic
B elastic but not plastic
C plastic but not elastic
D not elastic and not plastic
A spring of original length 100mm is compressed by a force. The graph shows the variation of the length L of the spring with the compressing force F.
What is the energy stored in the spring when the length is 70 mm?
A 0.090 J
B 0.21 J
C 0.27 J
D 0.63 J
The Young modulus of steel is determined using a length of steel wire and is found to have the value E. Another experiment is carried out using a wire of the same steel, but of twice the length and half the diameter.
What value is obtained for the Young modulus in the second experiment?
A 1/4 E
B 1/2 E
C E
D 2E
A piece of copper is drawn into a continuous wire.
What behaviour is the copper exhibiting?
A brittle only
B elastic only
C plastic only
D both brittle and elastic
The graph shows how the extension of a spring varies with the force used to stretch it.
What is the strain energy stored in the spring when the extension is 4.0 cm?
A 60 J
B 120 J
C 600 J
D 1200 J
What is the Young modulus of a metal?
A extension / force
B force / extension
C strain / stress
D stress / strain
A ductile material is stretched by a tensile force to a point beyond its elastic limit. The tensile force is then reduced to zero. The graph of force against extension is shown below.
Which area represents the net work done on the sample?
A X
B X + Y
C Y + Z
D Z
The variation of the extension x of a spring with applied force F is shown.
Which shaded area represents the work done when the extension is increased from x1 to x2?
A
B
C
D
Por favor, aguarde! Carregando...