# Elasticity

1. The spiral spring of a spring balance is 25.0 cm long when 5 N hangs on it and 30.0 cm long, when the weight is 10 N. What is the length of the spring if the weight is 3N assuring hook’s Law is obeyed? (a) 15.0cm (b) 17.0 cm (c) 0 cm  (d) 23.0 cm
2. In an experiment to determine Young’s Modulus for a wire, several loads are attached to the wire and the corresponding extensions measured. The tensile stress in each case depends on the (a) load and the extension (b) load and the radius of the wire (c) radius of the wire and the extension (d) extension and the original length of the wire A force of 15 N stretches a spring to a total length of 30 cm.
3. A force of 15N stretches a spring to a total length of 30 cm. An additional force of 10 N stretches the spring 5 cm further. Find the natural length of the spring. (a) 25.0 cm (b) 22.5 m (c) 20.0cm (d) 15.0cm
4. The energy contained in a wire when it is extended by 0.02 m by a force of 500 N is (a) 5J (b) I0J (c) 103J(d) 104J
5. A load of 20 N on a wire of cross-sectional area 8 x 10 7m2 produces an extension of 10-4m. Calculate Young’s modulus for the material of the wire if its length is 3 m. (a) 7.0 x 1011Nm-2 (b) 7.5 x 1011Nm-2 (c) .5 x 1011Nm-2 (d) 9.0 x 1011Nm-2
6. The tendon in a man’s leg is 0.01m long. If a force of 5 N stretches the tendon by 2.0 x 10’5 m, calculate the strain on the muscle. (a) 5 x 106 (b) 5 x 102 (c) 2 x 10-3 (d) 2 x 10-7
7. An elastic material has a length of 36cm when a load of 40N is hung on it and a length of 45cm when a load of 60 N is hung on it. The original length of the string is (a) 18 cm (b) 12 cm (c) 20 cm (d) 15cm
8. A string of length 4m is extended by 0.02m when a load of 0.4kg is suspended at its end. What will be the length of the string when the applied force is 15N? (a) 6.08m (b) 5.05m (c) 4.08 (d) 4.05m [g= 10ms-2]
9. If the stress on a wire is 107 Nm-2 and the wire is stretched from its original length of 10.00 cm to 10.05cm. The Young’s modulus of the wire (a) 5.0 x 104Nm-2 (b) 5.0 x 105Nm-2 (c) 2.0 x 108Nm-2 (d) 2.0 x 109Nm-2
10. A load of 5N gives an extension of 0.56cm in a wire which obey Hooke’s law what is the extension caused by a load of 20N? (a) 1.12cm (b) 2.14cm (c) 2.24cm (d) 2.62cm
11. The total length of a spiral spring when a mass of 20g is hung from its end is 14cm. while its total length is 16cm when a mass of 30g is hung from the same end. Calculate the un-stretched length of the spring assuming Hooke’s law is obeyed (a) 9.33cm (b) 10.00cm (c) 10.66cm (d) 12.00cm
12. A spring force constant 1500Nm-1J is acted upon by a constant force of 75N. Calculate the potential energy stored in the spring (a) 1.9J (b) 3.2J (c) 3.8J (d) 5.0J
13. The energy per unit volume of stretched wire given by the relation (E = energy per unit length) is (a) E= ½ strain x stress (b) E = ½ strain ÷ stress (c) E = 2strain x stress (d) E = 2strain ÷ stress
14. A point at which the molecules of a loaded wire begins to slide across each other resulting in a rapid increase in extension is the (a) yield point (b) elastic point (c) deformation point (d) proportional point
15. The force that produces an angular deformation without a change in volume of the material is referred to as (a) tensile stress (b) shear stress (c) compressive stress (d) bulk stress
16. Elasticity is the property which enables a material to (a) return exactly to its original shape and size on the removal of force (b) retain its deformation shape after the removal of an applied force (c) be drawn out in length (d) break without warning
17. The property of a material that allows it to be stretched into a wire is called (a) brittleness (b) malleability (C) fragility (d) ductility
18. A piece of rubber 10cm long stretches 6mm when a load of 100N is hung from it. What is the strain? (a) 60 (b) 6 x 10-2 (c) 6 x 10-3 (d) 0.6
19. A string of length 4m is extended by 0.02m when a load of 0.4kg is suspended at its end. What will be the length of the string when the applied force is 15N? [g = @ 10ms-2 (a) 6.08m (b) 5.05m (c) 4.098m (d) 4.05m