Answer:
50 h
Explanation:
The heat required (Q) to heat the water can be calculated using the following expression.
Q = c × m × ΔT = (4.184 kJ/kg.°C) × 1000 kg × (200°C - 60°C) = 5.9 × 10⁵ kJ
where,
c: specific heat capacity
m: mass
ΔT: change in the temperature
The solar collector has an area of 6 m² and the intensity delvered by sunlight is 550 W/m². The power (P) submitted by the collector is:
6 m² × 550 W/m² = 3 × 10³ W
The energy collected is transformed into heat. We know that:
P = E/t = Q/t
where
t: time
t = Q/P = 5.9 × 10⁸ J / (3 × 10³ J/s) = 2 × 10⁵ s × (1 h / 3600 s) = 50 h
Answer:
243 N
Explanation:
The formula for electromagnetic force is F= Kq1q2/r^2
where r is the distance between the charges, if the distance between the charges is reduced by 1/3 then F will increase by 9 [(1/3r)^2 becomes 1/9r which is 9F] so 27*9 is 243N
Answer:
D. They have the same number of valence electrons
Explanation:
In order to answer this question we need to understand the following.
- Valence electrons refers to the outermost electron(s) in the outermost energy level of an atom.
- Elements in the same group in the periodic table have the same number of valence electrons. For instance, group 2A elements have 2 valence electrons.
- The reactivity of elements in the periodic table is based on the number of valence electrons and the ease of gaining or losing electrons.
- Elements in the same group have similar valence electrons and therefore share similar chemical properties such as reactivity.
- Hence, elements in the same group have same number of valence electron and will thus have similar reactivity.
Answer:
the soap sinks because it is more dense than the duck.
It is released in the atmosphere by chemicals
