Everything Science Grade 12

CHAPTER 7. MECHANICAL PROPERTIES OF MATTER 7.3

Exercise 7 - 1

1. What causes deformation?


2. Describe Hooke’s Law in words and mathematically.


3. List similarities anddifferences between ductile, brittle and plastic(polymeric)
   materials, with specificreference to their force-extension graphs.


4. Describe what is meant by the elastic limit.


5. Describe what is meant by the limit of proportionality.


6. A spring of length 15cm stretches to 27 cm when a load of 0,4 N is applied to it.

(a) Calculate the springconstant for the spring.

(b) Determine the extension of the spring if a load of 0,35 N is appliedto it.

7. A spring has a springconstant of− 200 N.m−^1. By how much will it stretch if a
   load of 25 N is appliedto it?


8. A spring of length 20cm stretches to 24 cm when a load of 0,6 N is applied to it.

(a) Calculate the springconstant for the spring.

(b) Determine the extension of the spring if a load of 0,8 N is applied toit.

More practice video solutions or help at http://www.everythingscience.co.za

(1.) 01sv (2.) 01sw (3.) 01sx (4.) 01sy (5.) 01sz (6.) 01t0

(7.) 01t1 (8.) 01t2

7.3 Elasticity, plasticity, fracture, creep

ESCDO

Elasticity and plasticity ESCDP

Materials are classifiedas plastic or elastic depending on how they respond to an ap-

plied force. It is important to note that plasticsubstances are not necessarily a type