Practise Forces and elasticity. 19 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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A spring has a spring constant of 40 N/m. Calculate the force needed to stretch the spring by 0.15 m. Use the equation: force = spring constant × extension
6.0 N
Complete the sentence. Work done in stretching a spring is stored as ............ energy, as long as the spring is not permanently stretched.
Elastic potential.
Name the type of deformation in which the spring stays permanently stretched.
Inelastic deformation.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy6 marks
(a) A spring hangs from a clamp. A weight is hung from the bottom of the spring and the spring stretches. Why must more than one force act on the spring to stretch it? Tick (✓) one box.[1]
A single force would make the spring move instead of changing its shape.
A single force is always too small to stretch a spring.
Two forces are needed to double the extension.
The weight of the spring must be balanced first.
(b) Describe the difference between elastic deformation and inelastic deformation.[2]
(c) A spring has a spring constant of 40 N/m. Calculate the force needed to stretch the spring by 0.15 m. Use the equation: force = spring constant × extension[2]
(d) A diver stands on the end of a diving board and the board changes shape. Name the type of change of shape that happens to the diving board.[1]
Show the answer and mark scheme
(a)Answer: A single force would make the spring move instead of changing its shape.
(b)Answer: Elastic: returns to its original shape when the force is removed. Inelastic: does not return to its original shape.
elastic deformation: the object returns to its original shape / length when the force is removed
inelastic deformation: the object does not return to its original shape / length when the force is removed
(c)Answer: 6.0 N
F = 40 × 0.15
6.0 (N)
(d)Answer: Bending.
bending
Question 2Medium4 marks
An archer pulls back a bowstring, storing elastic potential energy in the bow.
(a) Describe the energy transfer that occurs from the moment the archer releases the bowstring to the moment just after the arrow leaves the bow.[2]
(b) Explain why the archer must apply a bigger force to pull the bowstring back further.[2]
Show the answer and mark scheme
(a)Answer: From the bow’s elastic potential energy store mainly to the arrow’s kinetic energy store; some is dissipated to the surroundings by heating and as sound.
energy is transferred from the elastic potential energy store of the bow mainly to the kinetic energy store of the arrow
some energy is dissipated to the surroundings: to thermal energy stores (because of friction and vibrations) and as sound
(b)Answer: A bigger extension of the bow needs a bigger force (like a spring, F = k e).
pulling the string back further gives the bow a greater extension (deformation)
the force needed increases with extension (like a spring, F = k e, if the bow stays within its limit of proportionality)
Question 3Hard10 marks
A student is given a spring and a set of 100 g slotted masses on a hanger.
(a) Plan an investigation to determine the spring constant of the spring and to find its limit of proportionality.[6]
(b) The student’s graph was a straight line through the origin up to a force of 6.0 N, which gave an extension of 0.080 m. Calculate the spring constant of the spring.[2]
(c) Calculate the elastic potential energy stored in the spring when the extension is 0.080 m. Use the Physics Equations Sheet.[2]
Show the answer and mark scheme
(a)
hang the spring from a clamp on a clamp stand with a metre rule clamped vertically beside it
measure the original length of the spring, using a pointer fixed to the bottom of the spring
add the masses one at a time (100 g has a weight of about 1 N) and record the new length each time
calculate each extension as new length − original length; read the ruler at eye level to avoid parallax
continue adding masses until the extensions stop increasing in equal steps
calculate the force on the spring for each load using W = m g
plot a graph of force against extension
the spring constant is the gradient of the straight-line section of the graph
the limit of proportionality is the point where the graph stops being a straight line
safety: wear eye protection and place a soft surface under the masses
Marked with levels of response: the full level descriptors are in the app.