Answer:
when the water is heated with immersion heater, the water becomes less dense due to which the warm water rises up and the cooler water fills it's space.
The figure shows the arrangement of system
The velocity of boat can be resolved in to two
Horizontal component = vcos θ = 2.50 cos 45 = 1.768 m/s
Vertical component = vsin θ = 2.50 sin 45 = 1.768 m/s
Due to horizontal component the boat arrive arrives upstream,
Total horizontal velocity = 1.768 - Vr, where Vr is the velocity of river.
Total time taken to cross the river = width of river/ Vertical component of velocity
t = 285/1.768 = 161.20 seconds
So 118 meter is traveled at a velocity of 1.768-Vr in 161.20 seconds
That is 118 = (1.768-Vr)*161.20
1.768 - Vr =0.732
Vr = 1.036 m/s
So velocity of river flow =1.036 m/s
The significant figures also known as the significant digits or precision of a number written in positional notation are digits that carry meaningful contributions to its measurements