Questions

Q1. A car travels along a circular racing track at a constant speed of 100 km/h.
Does it have uniform motion? Justify.

Q2. A simple pendulum is oscillating between two points, A and B. Describe its motion
in a few sentences by using the key words: periodic, time period, uniform,
interval, time, and displacement.

Q3. A spaceship travels 36,000 km in one hour.
Express its speed in km/s. What is its speed in m/s?

Solutions & Explanations

Solution to Q1

Even though the car’s speed is 100 km/h (constant in magnitude),
it is traveling in a circle, so its direction is continuously changing.
Therefore, the velocity is not constant.
Uniform motion requires both speed and direction to remain the same.
Hence, this situation is best described as uniform circular motion
rather than uniform motion.
The velocity vector keeps changing direction, so it is not uniformly directed motion.

Solution to Q2

A simple pendulum oscillates between two extreme points, A and B. The motion repeats
after a certain time interval, making it a periodic motion.
The time taken for one complete oscillation (A to B and back to A) is called the
time period. The pendulum’s displacement changes over time,
being maximum at A and B. Although the speed within one swing changes
(the pendulum moves faster near the middle and slower near the extremes),
the overall motion repeats itself with a fixed period. This means the motion is not
uniform in speed, but it is periodic.

Solution to Q3

A spaceship travels 36,000 km in one hour:

• Convert to km/s:

  1 hour = 3600 seconds.
  \[
  \text{Speed in km/s}
  = \frac{36000 \text{ km}}{1 \text{ hour}}
  \times \frac{1 \text{ hour}}{3600 \text{ s}}
  = 10 \text{ km/s}.
  \]

• Convert km/s to m/s:

  1 km = 1000 m, so
  \[
  10 \text{ km/s} = 10 \times 1000 \text{ m/s} = 10000 \text{ m/s}.
  \]

Therefore, the spaceship’s speed is 10 km/s
or 10,000 m/s.