Answer:
A scalar is completely described by magnitude only. A vector requires both magnitude and direction for its complete description.
Question 2
Give five examples each of scalar and vector quantities.
Answer:
Scalars: distance, speed, time, mass and temperature. Vectors: displacement, velocity, acceleration, force and weight.
Question 3
State the head-to-tail rule for addition of vectors.
Answer:
Draw the vectors in sequence so that the head of each vector meets the tail of the next. The resultant extends from the tail of the first vector to the head of the last vector.
Question 4
What are distance-time and speed-time graphs?
Answer:
A distance-time graph shows how distance changes with time. A speed-time graph shows how speed changes with time. Time is plotted on the horizontal axis in both graphs.
Question 5
Falling objects near Earth have the same constant acceleration. Does this imply that a heavier object falls faster than a lighter object?
Answer:
No. In the absence of air resistance, all freely falling objects have the same gravitational acceleration, regardless of mass, so they fall at the same rate under identical conditions.
Question 6
When vector quantities are written in scalar notation, how is their direction indicated?
Answer:
The direction is stated in words, such as north or downward, or by specifying an angle relative to a reference axis. A positive or negative sign may also indicate direction along a chosen axis.
Question 7
A body is moving with uniform speed. Will its velocity necessarily be uniform? Give a reason.
Answer:
No. Velocity is uniform only when both speed and direction remain constant. A body moving at constant speed along a curved path has changing velocity because its direction changes.
Question 8
Can a body have acceleration while moving with (i) constant velocity and (ii) constant speed?
Answer:
(i) No, constant velocity means neither magnitude nor direction changes, so acceleration is zero. (ii) Yes, at constant speed acceleration can exist if direction changes, as in circular motion.
Question 9
Define mechanics and name its two main branches.
Answer:
Mechanics is the branch of physics dealing with motion and the forces that change it. Its two main branches are kinematics and dynamics.
Question 10
Differentiate between kinematics and dynamics.
Answer:
Kinematics describes motion without considering the forces causing it, whereas dynamics studies forces and their effects on motion.