Motion Flashcards
What is the difference between distance and displacement?
Distance is how far something moves (not including direction), whereas displacement is measured in a straight line from the start point to the finish point and includes direction.
What is the difference between speed and velocity?
Speed is a scalar quantity. Velocity is a vector quantity as it includes direction.
What is the average walking speed?
1.5m/s.
What is the average running speed?
3m/s.
What is the average cycling speed?
6m/s.
What is the acceleration of a falling object near Earth?
9.8m/s².
What is circular motion?
An object moving along a circular path may have a constant speed, but its velocity is always changing as the direction of motion is constantly changing, resulting in a centripetal acceleration directed towards the centre of the circle.
What is Newton’s first law?
If the resultant force on an object is zero and the object is stationary, it will remain stationary. If the object is moving, it will continue to move at the same velocity.
What is Newton’s second law?
The acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object.
What is Newton’s third law?
Whenever two objects interact, the forces they exert on each other are equal and opposite.
What is meant by acceleration?
The change in the velocity in a given time.
What change of forces occur during a free fall of an object through a fluid?
Gravity (weight) pull it downwards and a drag force (air resistance) opposes its motion, which increases as the object speeds up, eventually reaching a point where the drag force balances the weight, resulting in a constant velocity called terminal velocity.
What is meant by terminal velocity?
The constant speed a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration.
What is inertia?
The tendency of objects to remain in their state of rest or uniform motion.
What are the speed forces involved in everyday transport?
When a car brakes or comes to a standstill in a short space of time, the forces required of the brakes are large. If the force is not large enough, the car may skid. There will also be large forces on the passengers from the seat.
What are the forces involved in everyday transport?
When a car suddenly changes direction, the forces required are large. If the force is not large enough, the car may skid.
What are the acceleration forces involved in everyday transport?
Seat belts, antilock brakes and airbags slow passengers down over a longer period of time, decreasing the forces acting on them.
How do brakes in a car work?
Friction between the brakes and the wheel decreases kinetic energy of the vehicle, increasing the thermal energy of the brakes and surroundings. The temperature of the brakes increases. The greater the speed of the vehicle, the more braking force is required to stop the vehicle in a certain distance.
What is stopping distance?
The sum of the distance travelled during the driver’s reaction time and the distance travelled.
What is thinking distance?
The distance a car travels while the driver reacts to a hazard and applies the brakes.
What is braking distance?
The distance a vehicle travels from the moment the brakes are applied until it comes to a complete stop, and it’s directly proportional to the square of the initial speed.
What factors may increase a person’s reaction time?
Tiredness, drugs, alcohol and distractions.
What factors may increase a vehicles braking distance?
Water, ice, gravel on the road, poor braking system conditions, poor tyre conditions and increased speed.
Why are large decelerations dangerous?
They can lead to loss of control, injuries to passengers and damage to vehicles due to the high forces involved, including potential overheating of brakes.
