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In this topic we investigate how pressure from your foot onto the ground varies with different footwear
In this topic we investigate how pressure from your foot onto the ground varies with different footwear
and investigate variables that affect the speed of a toy car rolling down a slope.
and investigate variables that affect the speed of a toy car rolling down a slope.
By the end of this topic you should know:
By the end of this topic you should know:
Pressure acts in a fluid in all directions. It increases with depth due to the increased weight of fluid, and results in an upthrust. Objects sink or float depending on whether the weight of the object is bigger or smaller than the upthrust.
Different stresses on a solid object can be used to explain observations where objects scratch, sink into or break surfaces.
If the overall, resultant force on an object is unbalanced, its motion changes and it slows down, speeds up or changes direction.
Use the formula:
speed = distance (m) / time (s)
or distance-time graphs, to calculate speed.
A straight line on a distance-time graph shows constant speed, a curving line shows acceleration.
The higher the speed of an object, the shorter the time taken for a journey.
By the end of this topic you should be able to:
By the end of this topic you should be able to:
Use diagrams to explain observations of fluids in terms of unequal pressure.
Explain why objects either sink or float depending upon their weight and the upthrust acting on them.
Explain observations where the effects of forces are different because of differences in the area over which they apply.
Given unfamiliar situations, use the formula to calculate fluid pressure or stress on a surface.
Use the formula: fluid pressure, or stress on a surface = force (N) / area (m2).
Use the idea of pressure changing with depth to explain underwater effects.
Carry out calculations involving pressure, force and area in hydraulics, where the effects of applied forces are increased.
Illustrate a journey with changing speed on a distance-time graph, and label changes in motion.
Describe how the speed of an object varies when measured by observers who are not moving, or moving relative to the object
Suggest how the motion of two objects moving at different speeds in the same direction would appear to the other.
Predict changes in an object's speed when the forces on it change.
By the end of this topic you should understand these key words:
By the end of this topic you should understand these key words:
Fluid: A substance with no fixed shape, a gas or a liquid.
Upthrust: The upward force that a liquid or gas exerts on a body floating in it.
Pressure: The ratio of force to surface area, in N/m2, and it causes stresses in solids.
Atmospheric pressure: The pressure caused by the weight of the air above a surface.
Speed: How much distance is covered in how much time.
Average speed: The overall distance travelled divided by overall time for a journey.
Relative motion: Different observers judge speeds differently if they are in motion too, so an object's speed is relative to the observer's speed.
Acceleration: How quickly speed increases or decreases.
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