Answer:
Ft = 17.48°C
Explanation:
Ft is the final temperature. However, ice absorbs heat during two process of melting and cooling and as such, there is no loss of heat to or from the surrounding hence by conservation of energy.
Therefore,
Heat absorbed by water of 20g = heat rejected by water of 265g.
So; M(ice)[C(ice) [(ΔT) + LH(ice) + C(water)(ΔT)] = C(water) M(water) (ΔT)
So, 20[(2.108) [0 - (-20)] + 333.5 + 4.187(Ft - 0)]] = (285)(4.187) (25 - Ft)
To get;
7513 + 83.74 Ft = 29832.4 - 1193.3 Ft
So factorizing, we get;
83.74 Ft + 1193.3 Ft = 29832.4 - 7513
So; 1277.04 Ft = 22319.4
So; Ft = 22319.4/1277.04 = 17.48°C
Well it's energy comes from the sun since the sun gives it sunlight to help it grow
Answer:
Object should be placed at a distance, u = 7.8 cm
Given:
focal length of convex lens, F = 16.5 cm
magnification, m = 1.90
Solution:
Magnification of lens, m = -
where
u = object distance
v = image distance
Now,
1.90 = 
v = - 1.90u
To calculate the object distance, u by lens maker formula given by:
u = 7.8 cm
Object should be placed at a distance of 7.8 cm on the axis of the lens to get virtual and enlarged image.
Answer: 10.58 C has flowed during the lightning bolt
Explanation:
Given that;
Time of flow t = 1.2 × 10⁻³
perpendicular distance r = 21 m
Magnetic field B = 8.4 x 10⁻⁵ T
Now lets consider the expression for magnetic field;
B = u₀I / 2πr
the current flow is;
I = ( B × 2πr ) / u₀
so we substitute
I = ( (8.4 x 10⁻⁵) × 2 × 3.14 × 21 ) / 4π ×10⁻⁷
= 0.01107792 / 0.000001256
= 8820 A
Hence the charge flows during lightning bolt will be;
q = It
so we substitute
q = 8820 × 1.2 × 10⁻³
q = 10.58 C
therefore 10.58 C has flowed during the lightning bolt
Answer:
B. Steam burns the skin worse than hot water because the latent heat of vaporization is released as well.
Explanation:
It is given that both steam and the boiling water when in contact with the skin cools down from 100 to 34 degrees Celsius.
For any substance of mass m, the heat required to change the temperature by
is
(S.I. unit = Joules).
where C, the specific heat capacity is the same and a constant for both the condensed steam and the boiling water.
But, there is a "hidden" energy (heat) released by the steam called latent heat
(given by mL, L = specific latent heat) which allows the phase transition (gas to liquid). While both of them are at the same temperature, their energy (heat) is different, which is why steam causes burns worse than boiling water