Correct Answer: D. Joint

Explanation

Joint demand refers to the relationship between two or more commodities or services when they are demanded together to satisfy one want. There is joint demand for cars and petrol, pens and ink, tea and sugar, etc. Jointly demanded goods are complementary.

Correct Answer: B. upstream and downstream

Explanation

The term upstream and downstream is used in the oil and gas industry to refer to the various activities of an oil or gas company. Upstream activities involves companies who extract or produce raw materials used in the production of oil and gas while Downstream industry are those who are involved in the distribution, sale and delivering of the refined products to the final customers.

Correct Answer: A. seven years

Correct Answer: B. Sweat gland

Correct Answer: C. 336

Explanation

\(^3{P}_3\) = \(\frac{8!}{8-3}!\)

= \(\frac{(8 * 7 * 6 * 5)!}{5!}\)

= 336

Correct Answer: A. increase in the pressure of the atmosphere

Correct Answer: A. worship of idols

Correct Answer: D. been

Explanation

(a) The term flooding:Flooding is the covering of the surface of the earth with water, resulting from temporary rise in the level of a river, lake or other water bodies.

(b) Causes: The causes are as follows:

(i) Heavy rainfall.

(ii) Blockage of drainage and water ways.

(iii) Encroachment on water courses by settlement.

(iv) Ground water coming out from over-saturated aquifer.

(v) Rivers overflowing their banks.

(vi) Release of excess water from reservoirs or dams.

(vii) The collapse of dams and rise in sea level.

(c) Effects: Flood would result in the following:

(i) Destruction of farmland.

(ii) Destruction of houses and properties.

(iii) Loss of life.

(iv) Shortage of food and high cost of food

(v) Outbreak of diseases and epidemics

(vi) Causes landslides and mudflow.

(vii) Temporary stoppage of economic activities such as schooling, marketing etc

(viii) Contamination of source of domestic water.

(d) Measures of control;

(i) Channelization

(ii) Enforcing environmental laws.

(iii) Clearing of drainage channels regularly.

(iv) Dredging of river course.

(v) Regular maintenance of dams.

Explanation

v = 0 m/s ; u = 30 m/s ; s = ? ; g = 10 m/s\(^{2}\).

(a) For maximum height, we use the formula

\(v^{2} = u^{2} - 2gs\)

\(s = \frac{u^{2} - v^{2}}{2g}\)

= \(\frac{30^{2} - 0^{2}}{2(10)}\)

= \(\frac{900}{20} = 45m\)

(b) Time to reach highest point:

\(v = u - gt \implies t = \frac{u - v}{g}\)

\(t = \frac{30 - 0}{10} = 3s\)

If the particle took 3s to get to the maximum height,

Time to reach the ground = 2(3) = 6s.

(c) From a height 40m above the ground, we use

\(s = ut - \frac{1}{2} gt^{2}\)

\(40 = 30t - 5t^{2}\)

\(5t^{2} - 30t + 40 = 0\)

\(5t^{2} - 20t - 10t + 40 = 0 \implies 5t(t - 4) - 10(t - 4) = 0\)

\((5t - 10)(t - 4) = 0 \implies \text{2s and 4s}\)

\(\therefore\) At times 2s and 4s, the height attained = 40m.