Posts Tagged ‘numerical’

Four persons K, L , M, N are initially at the four corners of a square of side d Problem

Four persons K, L , M, N are initially at the four corners of a square of side ‘d’. Each person now starts moving with a uniform speed ‘v’ in such a way that K always moves directly towards L, L towards M, M towards N and N towards K. After what time will they meet?

Gayathri asked.

Answer: Many students do not understand the real situation initially. Every time the persons are approaching each other and hence they will be moving closer and closer as they continue their walking. Finally they’ll reach the centre of the square to meet each other. I’ve tried to visualize the situation below.

From the diagram, we can make out that the resultant displacement by each when they meet will be d/√2 and the component of velocity of each towards the final point (the centre of the square) is v/√2.

Therefore,the time taken = displacement by the component of velocity in its direction = (d/√2) / (v/√2) = d/v

Problem from Kinematics

the distance between Ahmadabad and vadodara is 100 km.two trains set off simultaneously from Ahmadabad towards vadodara each other.the speed of these trains are 45kmh-1 And 30kmh-1.when will they cross each other?

A Numerical from Kinematics

Pooja asked:

an aeroplane flies 400km due west from city A to city B,then 300km north east to city C,and finally 100km north to city D. how far is it from city A to D?in what direction must the aeroplane had to return directly to city A from city D?

Answer will be posted soon

A Numerical for Practice

Akshay posted a numerical:
1. A disk of mass m=50g slides with zero initial velocity down an incline plane set at an angle 30 degrees to the horizontal. Having traversed the distance of 50 cm along the horizontal plane, the disc stops. Find the work performed by friction forces over the whole distance. Assume friction coefficient is 0.15 for both horizontal and incline planes.
Answer:- (-0.05J)