Force and Motion | Term 1 Unit 2 | 7th Science - Distance and Displacement | 7th Science : Term 1 Unit 2 : Force and Motion
Chapter: 7th Science : Term 1 Unit 2 : Force and Motion
Distance and Displacement
Distance and Displacement
Distance - The total length of a path
taken by an object to reach one place from the other is called distance.
Displacement – The shortest distance from the initial
to the final position of an object.
Both the
distance and displacement posses the same unit. The SI unit is meter (m).
Figure shows the motion of a person
between two places A and B.
He travels 10 km in first path. In
the second path, he travels 7 km.
The distance between A and B via
first path is 10 km. In the second path the distance is 7 km. The shortest
distance between the two places is 5 km represented as 2. So the displacement
is 5 km. (In east direction)
The path of an object travelling
from A to B is shown in figure. Total distance travelled by the object is 120
m. The displacement of the object is 40 m (south-east direction)
The path in which a rabbit ran is
shown in figure. Find the distance and displacement of it in the two figures.
Let us consider that each square is in an unit of one square meter. The rabbit
starts from point A and reaches the point B.
i) Distance - 17 m Displacement - 3m
ii) Distance - 27 m Displacement - 1m
When will the distance and
displacement be equal. Explain. But the starting and finishing points should be
different.
When travelling along the
straight line path the distance and displacement be equal.
When we represent the displacement,
we use a positive or negative sign depending on the direction with which it
travels.
Here we can consider the starting
point as A and while the object moves from A to B the displacement is
considered to be positive and from B to A it is negative.
Answer the following questions:
* Subha goes to the nearby playground from her home.
1. What is the distance she travelled?
2. What is her displacement?
* The distance
travelled by an object is 15 km and its displacement is 15 km. What do you
infer from this?
The distance of a person = 30 km Displacement = 0 km.
* The distance of a
person is 30 km and his displacement is 0 km. What do you inferfrom this?
(i.e.) The initial and the final position is same.
Nautical mile
Nautical mile is the unit for measuring the distance in the
field of aviation and sea transportation. One nautical mile is 1.852 km.
The unit for measuring the speed of aeroplanes and ships is
knot. One knot is the speed taken to travel one nautical mile in hour.
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