Archives

Is circular motion two dimensional

Motion in a plane is called two-dimensional motion. Circular motion is a two-dimensional motion.... View Article

what makes ice cubes melt faster

Salt is a very effective way to make ice cubes melt faster. The other methods would be to pour hot water over ice cubes, keeping it under... View Article

What is uncertainty with example

Uncertainty principle or Heisenberg uncertainty principle is the important theory in quantum physics. The principle states that it is impossible... View Article

What are 3 sources of nuclear energy?

Nuclear energy refers to the energy in the core or the nucleus of the atom. Nuclear energy can be produced by nuclear fission, nuclear fusion and... View Article

How does a DC voltmeter work

DC voltmeter is used in the measurement of DC voltage across any two points. DC voltmeter measures the peak value of the DC voltage. The DC... View Article

What does 200m mean on a multimeter

200 m on a multimeter means 200 milli. The voltage and the current can be set to 200 millivolts or 200 milliamperes on the multimeter.... View Article

Which metal cation is the best oxidizing agent

Pb2+ Cr3+ Fe2+ Sn2+ Answer: a. Pb2+ Reason A good oxidizing agent has the highest reduction potential.... View Article

Is copper glance a sulphide ore?

Yes, copper glance is a sulphide ore.... View Article

Which element in Group 1 has the highest density

The element with the highest density in group 1 is Francium. The atomic number is 87 and its density is expected to be around 2.48 g/cm3.... View Article

Does Arrhenius constant change with temperature

The Arrhenius equation for the rate constant is given as k = Ae-(Ea/RT) Here, k is the rate constant A is the pre-exponential factor Ea is the... View Article

Why anhydrous AlCl3 is used in Friedel Crafts reaction

Anhydrous AlCl3 is used in Friedel Crafts reaction since it is an electron-deficient molecule. It is Lewis acid. AlCl3 accepts Cl and becomes... View Article

How do you plot a hysteresis curve

When a substance is placed in a magnetic field it gets magnetised. The molecular magnets or magnetic dipoles orient themselves in the direction... View Article

Two pillars of equal height stand on either side of a road-way which is 60 m wide. At a point in the road-way between the pillars, the elevation of the top of pillars is 60° and 30°. The height of the pillars is

1) 15√3 m 2) 15/√3 m 3) 15 m 4) 20 m Solution: (1) 15√3 m AB and CD are the two pillars. BD = 60m ∠APB = 60o and ∠CPD = 30o In triangle... View Article

The angle of elevation of the top of the tower observed from each of the three points A B and C on the ground forming a triangle is the same i.e. ∠α. If R is the circumradius of the ∆A BC, then the height of the tower is

1) R sin α 2) R cos α 3) R cot α 4) R tan α Solution: (4) R tan α The triangle formed on the ground be ABC. From the figure, PQ is the tower... View Article

A person standing on the bank of the river observes that the angle of elevation of the top of a tree standing on the opposite bank is 60 degrees. When he was 40m away from the bank he found the angle of elevation to be 30 degrees. Find the width of the river.

1) 20 m 2) 10 m 3) 5 m 4) 1 m Solution: (1) 20 m Let x be the width of the river and h be the height of the tree. tan 60o = h / x √3 = h / x... View Article

The angle of elevation of an object from a point on the level ground is α. Moving d metres on the ground towards the object, the angle of elevation is found to be β. Then, the height (in metres) of the object is

1) d tan α 2) d cot β 3) d / (cot α + cot β) 4) d / (cot α - cot β) Solution: (3) d / (cot α + cot β) Assume the height of the object to... View Article

The angle of elevation of the Sun, if the length of the shadow of a tower is √3 times the height of the pole, is

1) 150o 2) 30o 3) 60o 4) 45o Solution: (2) 30o From the figure, let AB be the pole and BC - the shadow. θ is the angle of elevation. AB... View Article

A house of height 100 m subtends a right angle at the window of an opposite house. If the height of the window is 64 m, then the distance between the two houses is

1) 48 m 2) 36 m 3) 54 m 4) 72 m Solution: (1) 48 m Assume d to be a distance between the 2 houses. From the figure, in triangle BCD, 64... View Article

From a point on the ground, the angle of elevation of the top of a tower is observed to be 60 degrees. From a point, 40m vertically above the first point of observation, the angle of elevation of the top of the tower is 30 degrees. The horizontal distance from the point of observation is

1) - 20√3 m 2) √3/20 m 3) - √3/20 m 4) 20√3 m Solution: (4) 20 √3 m ∠QAP = 60o ∠QBR = 30o AB = PR = 40m AP = BR In triangle QAP, tan... View Article

The horizontal distance between two towers is 60 m and the angle of depression of the top of the first tower as seen from the top of the second is 30°. If the height of the second tower is 90 m, then the height of the first tower is

1) 90 m 2) (150 - 60√3)m 3) (150 - 20√3)m 4) None of these Solution: (4) None of these From the figure, DE and AB are the first and... View Article

M	T	W	T	F	S	S
					1	2
3	4	5	6	7	8	9
10	11	12	13	14	15	16
17	18	19	20	21	22	23
24	25	26	27	28	29	30
31