Q10 of 43 Page 85

The resultant of two vectors A and B perpendicular to the vector A and its magnitude is half of the magnitude of vector B. Find out the angle between A and B?

Let be the resultant of and.


So,


Now, is perpendicular to.


So, using Pythagoras theorem:


...1


Also, ...2


Putting 2 in 1, we get:





Now, the angle between A and B is (180 – Ɵ)


From the figure,


So, and (180 –) = 150°


So, anthe gle between A and B is 150°


More from this chapter

All 43 →
8

The velocity at the maximum height of a projectile is half of its initial velocity of projection u. Its range on the horizontal plane is

 9

The ceiling of a hall is 40m high. For maximum horizontal distance, the angle at which the ball may be thrown with speed 56 ms–1 without hitting the ceiling is

 11

A stone projected from the ground with the certain speed at an angle α with horizontal attains maximum height H1 when it is projected with same speed at an angle α with vertical attains height H2. The horizontal range of a projectile is?

 12

The range R of a projectile is same when its maximum heights are h1 and h2. What is the relation between R, h1, h2?