Flashcards
P4 - Explaining Motion
Cards in this deck (34)
- 1What two words together mean 'two forces that arise from the same interaction'.interaction forces
- 2Two properties of an interaction pair always remain the same. What are they?The two forces are always equal in size and opposite in direction.
- 3What is the name for the force that arises from two objects touching?Contact forces.
- 4What is action-at-a-distance? Give two examples.The forces that sometimes occur between objects that aren't touching - such as a magnetism and gravity.
- 5What are the two properties of action-at-a-distance forces that are different from contact forces?Action-at-a-distance forces act all the time, but grow weaker with distance.
- 6How do objects, such as cars, get moving?An interaction force between them, such as a car's wheels turning and the ground pushing the wheels in response.
- 7If a car is stuck on ice it doesn't move. Why is this?There's no friction, which stops car wheels from slipping.
- 8What causes friction?The roughness of two surfaces sliding past one another. The grooves in one surface interlock with the grooves in another.
- 9What two things does the amount of friction depend on?The weight of the box and the roughness of the two surfaces.
- 10What is the sum of all objects acting on an object called?The resultant force.
- 11What is 'the force exerted by a hard surface on an object that presses on it'?The 'reaction' of the surface.
- 12Describe the phases that occur when a ball is dropped in freefall. (3 phases)1. The ball is released and begins falling. 2. It's speed steadily increases, so it has a steady acceleration. 3. It lands and it's reaction of the surface causes it to bounce with equal and opposite force.
- 13What 4 factors affect air resistance?Larger mass, larger surface area, faster movement and more air particles per cm cubed increases air resistance.
- 14What is the difference between distance and displacement?Distance is how long a journey is, whilst displacement is how far the end point is from the start point.
- 15What two words mean 'the speed of an object at a given moment' and how is this worked out?instantaneous speed is measured by taking a short time interval and measuring the average time for that.
- 16In a distance-time graph, what does a slope, a curve and a horizontal line mean?Slope means steady speed, a curve means acceleration or deceleration and a horizontal line means the object isn't moving.
- 17When is it possible to draw a displacement-time graph?When an object moves in a straight line.
- 18What makes a displacement-time graph and a distance-time graph different?The direction of motion - if an object travels in one direction the two graphs are the same, if the objects reverses direction the two graphs are different, and displacement shows this but distance doesn't.
- 19What does a slope, a curve and a horizontal line mean on a speed-time graph?A slope means acceleration or deceleration at a constant rate, a curve means acceleration or deceleration at an inconstant rate and a horizontal line means a steady speed.
- 20How does a velocity-time graph show when an object begins travelling in the opposite direction?The line of the graph becomes negative.
- 21What does a force acting upon an object cause?A change in motion.
- 22What's the equation that works out momentum?momentum = mass x velocity
- 23Why do crumple zones on cars work?The change of momentum is fixed, so when the time the crash takes increases the resultant force has to decrease to equal the same change of momentum.
- 24Aside from crumple zones, name two other safety features used in cars and motorcycles.Motorcycle helmet and car seatbelts.
- 25If a resultant force on an object is 0N, what happens to the object?Nothing - if it's not moving it doesn't move, and if it's already moving it continues at the same speed.
- 26What is the force pushing an object forwards called?driving force
- 27What are forces such as air resistance and friction called?counter-force(s)
- 28What is the energy of a moving object called?kinetic energy
- 29What's the equation that explains how work done by a force is calculated?work done by a force = force x distance moved in the direction of the force
- 30When an object is moved vertically upwards, what does it gain?gravitational potential energy (GPE)
- 31What's the equation for GPE, with units?GPE (joules, J)= weight (newtons, N) x vertical height difference (metres, m)
- 32What's the equation for kinetic energy, with units?kinetic energy (joules, J) = 1/2 x mass (kilograms, kg) x velocity squared (metres per second, m/s)
- 33What is the idea that 'energy is never used up, just passed on to another object' called?conservation of energy
- 34What happens when gravitational energy decreases?kinetic energy decreases (and vice versa)
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- Cambridge IGCSE Physics Flashcards on P4 - Explaining Motion, created by franimal on 20/11/2013.
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