Pls tell how to do this - Physics - Motion

Question

Pls tell how to do this??

Rohit Babu · Accepted Answer

Dear Student, Suppose, a farmer moves along the boundary of a square field of side 10 m in 40 s as shown in the figure given below

Distance covered by the farmer as he moves from A to B to C to D to A, along the boundary wall of square field = Perimeter of Square field = 4 x side of square field = 4 × 10 m = 40 m ∴ speed of farmer = 40 m/40 s = 1 m/s Distance covered by farmer in 2 minutes 20 seconds = Speed × Time = 1 m/s × [(2×60) s + 20 s] = 140 m Number of round in covering 40 m of distance along the boundary wall = 1 round ∴ Number of round in covering 140 m of distance along the boundary wall = 1×140 /40 rounds = 3 5 round = 3 1/2 rounds Which means the farmer will be at point C just diagonally opposite of point A

∴ Relative Displacement of farmer from point A at the end of 3 ¹/₂ round will be = length of AC
which can be determined by the mathematical theorem as given below :

A C = \sqrt{A B^{2} + B C^{2}} \Rightarrow A C = \sqrt{10^{2} + 10^{2}} = \sqrt{200} = \sqrt{100 \times 2} = 10 \sqrt{2} = 14.14 m

Regards

Distance covered by the farmer as he moves from A to B to C to D to A, along the boundary wall of square field	= Perimeter of Square field
	= 4 x side of square field
	= 4 × 10 m
	= 40 m

∴ speed of farmer	= 40 m/40 s
	= 1 m/s
Distance covered by farmer in 2 minutes 20 seconds	= Speed × Time
	= 1 m/s × [(2×60) s + 20 s]
	= 140 m
Number of round in covering 40 m of distance along the boundary wall	= 1 round
∴ Number of round in covering 140 m of distance along the boundary wall	= 1×140 /40 rounds
	= 3.5 round
	= 3 ¹/₂ rounds