Sarang

A man wants to cross a river 500m wide. His rowing speed in still water is 3kmph. The river flows at a speed 2 kmph. If man's walking speed on the shore is 5 kmph, (a) Find the path he should take to get to the point directly opposite to his starting point in shortest time.(b) How long does it take to get there?

A swimmer wishes to cross a 500 m wide river flowing with 5 km/h. His speed with respect to water is 3km/h. If heads in a direction making an angle theta with the flow, find the time he takes to cross the river.

Answer is (10/sin theta) minutes.

Velocity ?

A) 50 km/h north-west

B) 50 square root 2 km/h north-east

C) 50 square root 2 km/h south-west

D) 50 square root 2 km/h south-east

2) A vector F1 is along positive x- axis. If its vector product with another vector F2 is zero, then F2 could be

A) 4 i

B) -( i + j)

C) (j + k)

D) -(4 j)

3) A body moves at a speed of 100 km/h in north direction. After Travelling 200 km it starts moving in east direction with same speed. Assume time taken in moving from north to east direction is very less. Finally it moves 200 km in east direction. What is the acceleration of the body ?

A) 100 km/h^2

B) 100 square root of 2 km/h^2

C) 25 square root of 2 km/h^2

D) None of these

Please explain how you got the answer.Thank you.

Let an acute angled triangle with vertices A(x1,y1), B(x2,y2), C(x3,y3) in 1st quadrant. If x1, x2, x3 are in A.P. then y1, ,y2, y3 can be in

i) A.P.

ii) G.P.

iii) H.P.

iv) None.

What is A.P., G.P., H.P.? Please explain.

1) An elevator is descending with uniform acceleration.To measure the acceleration, a person in the elevator drops a coin at the moment the elevator starts.The coin is 6 ft. above the floor of the elevator at the time it is dropped.The person observes that the coin strikes the floor in 1 second.Calculate from this data the acceleration of the elevator.

2)A ball is thrown horizontlly from a point 100m above the ground with speed 20m/s.Find (a) the time it takes to reach the ground, (b) the horizontal distance it travels before reaching the ground, (c) the velocity(direaction and magnitude) with which it strikes the ground.

a) SO2 + 2 H2S = 3S + 2 H2O

b) 5 SO2 + 2 KMnO4 + 2 H2O = K2SO4 + 2 MnSO4 + 2 H2SO4

the best answer than it wil be unfair.

contributor?Please answer my question.

as that of original mixture.Calculate percentage of NaI in the mixture.

12% of water. Find the percentage of silica in the original sample.

2) NaI + NaCl + H2SO4 --->.......................................................

of oxalic acid was heated with concentrated sulphuric acid?

(COOH)2 --> CO + CO2 + H2O.

excess amount of an AgNO3 soution was added to this solution. The precipitate formed was washed and dried.Its mass was 0.287g.Find the mass of NaCl in the initial sample. Please please help me!

0.9g/mL.If this solution contains 30% of NH3 by weight, calculate its volume.

O2 stands for oxygen molecule.