Differentiate between positive and negative acceleration.
Answer:
Acceleration is positive when velocity increases in the selected positive direction. It is negative, or deceleration, when velocity decreases.
Question 32
Differentiate between uniform and non-uniform acceleration.
Answer:
Uniform acceleration has a constant rate of change of velocity. Non-uniform acceleration changes in magnitude, direction or both.
Question 33
Why is the independent variable plotted on the x-axis?
Answer:
The independent variable is controlled or progresses on its own, while the dependent variable changes in response to it; therefore convention places it on the horizontal x-axis.
Question 34
What information does a horizontal distance-time graph provide?
Answer:
Distance remains unchanged as time passes, so the object is at rest.
Question 35
What information does a straight rising speed-time graph provide?
Answer:
Speed increases by equal amounts in equal intervals of time, indicating uniform acceleration.
Question 36
What does the area under a speed-time graph represent?
Answer:
It is numerically equal to the distance travelled during the selected time interval.
Question 37
Write the three equations of uniformly accelerated motion.
Answer:
vf = vi + at; S = vit + 1/2 at2; and vf2 = vi2 + 2aS.
Question 38
State three assumptions used with the equations of motion.
Answer:
Motion is along a straight line, acceleration is uniform and a consistent positive direction is selected.
Question 39
What is free fall acceleration and in which direction does it act?
Answer:
It is the acceleration of an object falling under gravity alone. It acts vertically downward and is approximately 10 m/s2 near Earth.
Question 40
What is meant by the universal speed limit?
Answer:
According to special relativity, no object with mass can reach or exceed the speed of light, approximately 3 x 108 m/s.