SP1 - Motion Flashcards
What are vectors?
Vectors are quantities with both magnitude and direction (e.g. weight)
What are scalars?
Scalars are quantities which have only magnitude (e.g. mass)
What is the difference between distance and displacement?
Distance is a scalar. It is the distance travelled from one point to another.
Displacement is a vector, it is the distance travelled in a straight line from one point to another.
Therefore, the displacement can never be longer than the distance.
What is difference between weight and mass?
Mass is a scalar, it is the amount of matter something contains.
Weight is a vector, it is the force of energy acting on an object in a certain direction.
What is the equation for speed?
Average speed (m/s)= distance (m) / time (s)
What does a horizontal line mean on a distance/time graph?
It means the object is stationary.
What does a straight, sloping line mean on a distance/time graph?
It means the object is travelling at a constant speed.
How do you calculate the speed of an object from a distance/time graph?
The speed is equal to the gradient of the line, which is calculated using the equation gradient = change in y / change in x
What is the equation for acceleration not involving distance?
Acceleration (m/s^2) = change in velocity (m/s) / time (s)
What is the equation for acceleration involving distance?
v^2-u^2=2ax
Final velocity ^2 (m/s) - initial velocity ^2 (m/s) = 2 x acceleration (m/s^2) x distance (m)
What is the value for acceleration due to gravity on Earth?
Around 9.81 m/s^2 but is rounded to 10 in most calculations
What does a horizontal line mean on a velocity/time graph?
It means the object is travelling at a constant velocity.
What does a sloping line mean on a velocity/time graph?
It means the object is accelerating (if the line is downwards to the right it is decelerating), if the line is straight it is accelerating at a constant rate, if it is curved, it is increasing its acceleration.
How do you find the acceleration from a velocity/time graph?
The acceleration is equal to the gradient, which can be calculated using the equation gradient = change in y / change in x. If the line is curved, you can draw a tangent to it and calculate its gradient to find the acceleration.
What does a line below the horizontal axis mean on a velocity/time graph?
It means the object is travelling in the opposite direction (so has negative velocity)
How do you calculate distance travelled from a velocity/time graph?
The area under the line is the distance travelled. To work this out, you can split the area into shapes you can calculate the area of (e.g. rectangles and triangles). If there is a curved line you have to count the squares and estimate the distance.
What is the equation for weight?
Weight (N) = Mass (kg) x gravitational field strength (N/kg)
What is the ruler drop test?
One person holds a ruler and a stopwatch, the other holds their hand around the 0 cm mark, they drop the ruler and the other person has to grip it. Measures human reaction time (between 0.2-0.9 seconds) and you can calculate speed using s=d/t
What are light gates for?
Light gates measure acceleration. They are an improvement on using a ruler and stopwatch then using s=d/t then a=v-u/t because it removes human error and the human reaction time.
