speed

knot

metre/second²

The motion of a car on a crowded road.

The motion of a freely falling object.

No, displacement is a vector quantity as it depends on direction.

When an object travels is a circular path (ie. the initial and positions are same).

There are two possible answers:
Velocity gives an idea of how fast the position changes. or Acceleration gives an idea of how fast the velocity changes.

An object moving in uniform circular motion is moving around the perimeter of the circle with a constant speed. While the speed of object is constant, its velocity is changing, Ex: Merry-go-round, roller coaster, planets orbiting the sun.

Speed is the rate of change of distance
Formula: Speed = distance /time
Unit is meter/second (m/s)

The centre of gravity of an object is the point through which the entire weight of the object appears to act.

(a) A bus moving with constant speed.

\(\begin{array}{|l|c|c|c|c|c|} \hline \text { Time } & 0 & 1 & 2 & 3 & 4 \\ \hline \text { Distance } & 0 & 10 & 20 & 30 & 40 \\ \hline \end{array}\)
(b) A car parked on road side.

 

\(\begin{array}{|l|c|c|c|c|c|} \hline \text { Time } & 1 & 2 & 3 & 4 & 5 \\ \hline \text { Distance } & 20 & 20 & 20 & 20 & 20 \\ \hline \end{array}\)

Acceleration of the bus (a) = 1 m/s²
Initial velocity (u) = 50 km/s
= 50 \(\times\) 1000 = 50000 m/s
Final velocity (v) = 100 km/s
= 100 \(\times\) 1000 = 10000 m/s
1 km = 1000 m
\(\text { Acceleration } =\frac{V-u}{t} \)
\(1 =\frac{100000-50000}{t} \)
\(t =100000-50000 \)
\(t =50000 \mathrm{~s} \)

Speed (S) = 2m / s
Time (t) = 15 minutes = 15 \(\times\) 60 = 900 s
Distance (D) = ?
\(S = \frac{D}{t} \) 
D = S \(\times\) t
D = 2 \(\times\) 900
D = 1800 m
Distance between her house and school = 1800 m.