Question

2. A farmer moves along the
boundary of a square field of side
10 m in 40 s. What will be the
magnitude of displacement of the
farmer at the end of 2 minutes 20
seconds from his initial position?
3. Which of the following is true for
displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than
the distance travelled by the object.​

Answer 1

2. Side of the square = 10 m

Perimeter of the square = 4×10 = 40 m

He completes 1 round in 40 s.

So, speed = 40/40 = 1 m/s

So, distance covered in 2 min 20 s or 140 s is = 140 × 1 = 140 m

Number of rounds of the square completed in moving through 140 m is = 140/40 = 3.5

In 3 rounds the displacement is zero.

In 0.5 round the farmer reaches the diagonally opposite end of the square from his starting point.

Displacement = AC = (AB + BC ) = (100+100) = 10√2 m.......:)

3. both are false....

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Answer 2

Answer 2.

A farmer moves along the boundary of a square field of side 10 m in 40 sec.

Side of square = 10 m and time = 40 sec

Perimeter of square = 4 × side

= 4 × 10 = 40 m

We have to find the displacement of the farmer at the end of 2 min 20 sec.

Time = 2 min 20 sec

1 min = 60 sec

2 min = 2(60) = 120 sec

= 120 sec + 20 sec = 140 sec

Now,

In 1 sec distance covered by farmer = 40/40 = 1 m

So, in 140 sec distance covered by farmer = 1 × 140 = 140 m

Number of rotations to cover 140 m along the boundary = Distance/Perimeter

= 140/40 = 3.5 rounds

Therefore, the farmer takes 3.5 revolutions.

Let us assume that farmer is at the point A from the origin of the square field.

Now,.

Displacement = diagonal of square

And from above we have a side of square = 10 m

So, displacement = 10√2 m

Answer 3.

a) Displacement can be zero, if the initial and final points of the object or body are same.

Magnitude of displacement can't be greater than the distance travelled by the object or body.

Both are false.