Figure shows the force- extension graph for a wire that is stretched and then released. Force-extension graph for a wire. (a) Which point shows the limit of proportionality?

Proportionality limit is point on graph upto which the graph is a straight line (Hooke's law is followed) and force is directly proportional to extension. Therefore, point B shows limit of proportionality.

Figure shows the force- extension graph for a wire that is stretched and then released. Force-extension graph for a wire. (b) Which point shows the elastic limit ?

Elastic point is a point on force-extension graph from which stretched material can regain its original length. It lies beyond proportionality limit. Therefore in given graph point C is elastic limit.

Figure shows the force- extension graphs for four springs, A, B, C and D. Force-extension graphs for four different springs. (a) State which spring has the greatest value of force constant.

F = - k x where F is force , k is force constant and x is extension or compression. Since spring D undergoes the least extension therefore, it has the greatest value of force constant.

Figure shows the force- extension graphs for four springs, A, B, C and D. Force-extension graphs for four different springs. (b) State which is the least stiff.

According to Hooke's law F = - k x where F is force , k is force (spring) constant and x is extension or compression. Also, that spring A has the greatest extension therefore, spring A is least stiff.

Figure shows the force- extension graphs for four springs, A, B, C and D. Force-extension graphs for four different springs. (c) State which of the four springs does not obey Hooke's law.

∵ F = - k x Therefore, force extension graph of spring which obey Hooke's law must be a straight line. So we can conclude from the graph that spring A and C do not obey Hooke's law for given range of force.

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(b) A submarine floats at rest under the water. To rise to the surface compressed air is used to push water out of its 'ballast' tanks into the sea. Why does this cause the submarine to rise?

Important Questions on Matter and Materials

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Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Questions>Q 8

A boat has a uniform cross-sectional area at the water line of

750 m^{2}

. Fifteen cars of average mass

1200 kg

are driven on board. Calculate the extra depth that the boat sinks in water of density

1000 kg m^{- 3}

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Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Questions>Q 10

A balloon of volume

3000 m^{- 3}

is filled with hydrogen of density

0.090 kg m^{- 3}

. The mass of the fabric of the balloon is

100 kg

. Calculate the greatest mass that the balloon can lift in air of density

1.2 kg m^{- 3}

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Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Question>Q 11

Figure shows the force- extension graph for a wire that is stretched and then released.

Question Image

Force-extension graph for a wire.

(a) Which point shows the limit of proportionality?

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Question>Q 11

Figure shows the force- extension graph for a wire that is stretched and then released.

Question Image

Force-extension graph for a wire.

(b) Which point shows the elastic limit ?

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Question>Q 12

Figure shows the force- extension graphs for four springs, A, B, C and D.

Question Image

Force-extension graphs for four different springs.

(a) State which spring has the greatest value of force constant.

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Question>Q 12

Figure shows the force- extension graphs for four springs, A, B, C and D.

Question Image

Force-extension graphs for four different springs.

(b) State which is the least stiff.

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Question>Q 12

Figure shows the force- extension graphs for four springs, A, B, C and D.

Question Image

Force-extension graphs for four different springs.

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AS and A Level

IMPORTANT

Physics for Cambridge International AS & A Level Coursebook 3rd Edition Digital Access>Chapter 7 - Matter and Materials>Questions>Q 13

List the metals in Table from stiffest to least stiff.

Question Image

The Young modulus of various materials. Many of these values depend on the precise composition of the material concerned. $(Remenber 1 GPa = 10^{9} Pa)$

(b) A submarine floats at rest under the water. To rise to the surface compressed air is used to push water out of its 'ballast' tanks into the sea. Why does this cause the submarine to rise?

Important Questions on Matter and Materials

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