The total time is 6.45 s
Explanation:
The motion of the car is a uniformly accelerated motion, so we can use suvat equations.
In the first part,
(initial velocity)
(acceleration)
(time of the first part)
So, we can find the velocity of the car after the first part, by using
This is therefore the initial velocity of the second part:
(acceleration in the second part)
(final velocity)
And therefore,
So, the total time is
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Answer:
(a) 1317.44 W/m²
(b) 1.74×10¹⁵ litres of heating oil
(c) -20.63°C
(d) Energy storage in the Earth and the air
Explanation:
The parameters given are;
Luminosity of the Sun = 3.828 × 10²⁶ Watt
Distance of the Earth from the Sun, d = 152.06 × 10⁶ km
The radius of the Sun = 696 × 10³ km
The radius of the Earth, = 6730 km
The surface area of the Sun = 12000 × Surface area of the Earth
The surface area of the Sun = 6.09 × 10¹² km²
Cross sectional area of the Earth = 1.27 × 10⁴ m² = 0.0127 km²
By the inverse square law, we have;
Where:
R = Solar radiation reaching the Earth
Therefore;
Hence, the energy, E, reaching the Earth in a day is given as follows;
E = R × 4×πײ×60×60×24 = 1317.44 × 4 × π × 6730000² × 60×60×24
E = 6.479×10²² Joules
(b) The number of litres of heating oil is therefore;
6.479×10²² J ÷ (37.3×10⁶ J/litre) = 1.74×10¹⁵ litres of heating oil
(c) 30% of the Energy is reflected, therefore;
0.7 × 6.479×10²² Joules = 4.54×10²² Joules reaches the Earths surface
From Stefan-Boltzmann law, we have;
Where:
α = 0.3
σ = Stefan-Boltzmann constant = 5.6704×10⁻⁸ W/(m²·K⁴)
Therefore;
(d) The heat storage in the Earth and the air