Water has a specific heat capacity nearly nine times that of iron. suppose a 50-g pellet of iron at a temperature of 200∘c is dropped into 50 g of water at a temperature of 20∘c.
when the system reaches thermal equilibrium, its temperature will be
a. closer to 20∘c.
b. halfway between the two initial temperatures.
c. closer to 200∘c.

a. closer to 20∘C

Explanation:

= mass of pallet = 50 g = 0.050 kg

= specific heat of pallet = specific heat of iron

= Initial temperature of pellet = 200 C

= mass of water = 50 g = 0.050 kg

= specific heat of water

= Initial temperature of water = 20 C

= Final equilibrium temperature

Also given that

Using conservation of energy

Energy gained by water = Energy lost by pellet

hence the correct choice is

a. closer to 20∘C

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s