1.5 Forces
1.5.1 Effects of forces
Effects of forces:
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Changes size of object
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Changes shape
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Changes the speed of motion
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Changes direction of motion
Load–extension practical:
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Take a spring and suspend it from a clamp & stand.
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Attach a ruler to the clamp.
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Add a pointer for more accurate readings to prevent parallax error.
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Measure initial position of pointer.
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Add 100g masses.
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Continue until limit of proportionality and measure the position of pointer each time.
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Repeat to get accurate results.
Resultant forces acting along the same straight line:
An object either remains at rest or continues in a straight line at constant speed unless acted on by a resultant force.
Friction – The force between two surfaces that may impede motion and produce heat.
Friction (drag) acts on an object moving through a liquid.
Friction (drag) acts on an object moving through a gas (e.g. air resistance).
Spring constant – Force per unit extension
k=F/x
Limit of proportionality – The maximum force that can be applied to a spring so that it can still return to its original length/shape when the force is removed.
When the limit of proportionality is exceeded, the spring will no longer bounce back to its original shape after the force is removed.
F=ma
Motion in a circular path due to a force perpendicular to the motion:
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Speed increases if force increases, with mass and radius constant.
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Radius decreases if force increases, with mass and speed constant.
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An increased mass requires an increased force to keep speed and radius constant.