At 20 ◦C, a rod is exactly 20.05 cm long on a steel ruler. Both the rod and the ruler are placed in an oven at 270 ◦C, where the rod now measures 20.11 cm on the same ruler. What is the coefficient of linear expansion for the material of which the rod is made? Take αsteel = 1.2 × 10−5 K−1 .

The coefficient of expansion is

∝=1.56*10^-5/C

Explanation:

The problem is based on linear expansivity

The linear expansivity of a solid is the fractional increase in length per unit degree rise in temperature.

It is given as

∝=ΔL/ΔT

Given L1=20.5cm to m =20.5/100

=0.205m

L2=20.11cm to m= 20.11/100

= 0.2011nlm

T1=20°c

T2=270°c

∝=0.2011-0.205/270-20

∝=0.0039/250

∝=0.0000156

∝=1.56*10^-5/C

b

explanation:

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min