Unit Vectors, Adding Vectors by Components

Author:Resnick & Halliday
JEE Main
IMPORTANT

Important Questions on Unit Vectors, Adding Vectors by Components

EASY
IMPORTANT

In the figure, a vector a with a magnitude of 15.0 m is directed at angle θ=56.0° counter-clockwise from the +x-axis. What are the components (a) ax and (b) ay of the vector? A second coordinate system is inclined by an angle θ'=18.0° with respect to the first. What are the components (c) a'x and (d) a'y in this primed coordinate system?

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HARD
IMPORTANT

Here are two vectors :

a=4.0 m i^-3.0 m j^ and b=6.0 m i^+8.0 m j^

What are (a) the magnitude and (b) the angle (relative to i^) of a? What are (c) the magnitude and (d) the angle of b? What are (e) the magnitude and (f) the angle of a+b ; (g) the magnitude and (h) the angle of b-a ; and (i) the magnitude and (j) the angle of a-b? (k) What is the angle between the direction of b-a and a-b?

HARD
IMPORTANT

Typical backyard ants often create a network of chemical trails for guidance. Extending outward from the nest, a trail branches (bifurcates) repeatedly, with 60° between the branches. If a roaming ant chances upon a trail, it can tell the way to the nest at any branch point. If it is moving away from the nest, it has two choices of path requiring a small turn in its travel direction, either 30° leftward or 30° rightward. If it is moving toward the nest, it has only one such choice. The given figure shows a typical ant trail, with lettered straight sections of 2.0 cm length and symmetric bifurcation of 60°. Path v is parallel to the y axis. What are the (a) magnitude and (b) angle (relative to the positive direction of the superimposed x axis) of an ant's displacement from the nest (find it in the figure) if the ant enters the trail at point A? What are the (c) magnitude and (d) angle if it enters at point B ?

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HARD
IMPORTANT

Two beetles run across flat sand, starting at the same point. Beetle 1 runs 0.50 m due east, then 0.70 m at 30° north of due east. Beetle 2 also makes two runs, the first is 1.6 m at 40° east of due north. What must be (a) the magnitude and (b) the direction of its second run if it is to end up at the new location of beetle 1?

EASY
IMPORTANT

If d1 + d2 =5d3 , d1-d2 =3d3 and d3=2i^+4j^. Then what are, in unit-vector notation, (a) d1 and (b) d2?

HARD
IMPORTANT

What is the sum of the following four vectors in (a) unit-vector notation, (b) as magnitude, and (c) as an angle?

A=2.00 m i^+3.00 m j^     B : 4.00 m at +65.0°

C=-4.00 m i^+-6.00 m j^     D : 5.00 m at -235°

HARD
IMPORTANT

Starting from an oasis, a camel walks 25 km in a direction 30° south of west and then walks 30 km towards the north to a second oasis. What is the direction from the first oasis to the second oasis?

HARD
IMPORTANT

Vector A which is directed along an x-axis, is to be added to vector B. Which has a magnitude of 6.0 m. The sum is a third vector that is directed along the y-axis, with a magnitude that is 3.0 times that of A. What is that magnitude of A?

HARD
IMPORTANT

If b=3.0 i^+4.0 j^ and a=i^-j^, what is the vector having the same magnitude as that of b and parallel to a?

HARD
IMPORTANT

(a) What is the sum of the following four vectors in unit-vector notation? For that sum what are (b) the magnitude, (c) the angle in degrees, and (d) the angle in radians?

E:6.00 m at+0.900 rad      F:5.00 m at-75.0°    G:4.00 m at+1.20 rad      H:6.00 m at-210°

 

HARD
IMPORTANT

An ant, crazed by the sun on a hot Texas afternoon, darts over an xy-plane scratched in the dirt. The x and y components of four consecutive darts are the following, all in centimeters 30.0, 40.0, bx, -70.0, -20.0, cy, -80.0, -70.0. The overall displacement of the four darts has the xy-components -140, -20.0. What are (a) bx and (b) cy? What are the (c) magnitude and (d) angle(relative to the positive direction of the x-axis) of the overall displacement?

MEDIUM
IMPORTANT

An explorer is caught in a whiteout (in which the snowfall is so thick that the ground cannot be distinguished from the sky) while returning to the base camp. He was supposed to travel due north for 4.8 km, but when the snow clears, he discovers that he actually traveled 7.8 km at 50° north of due east. (a) How far and (b) in what direction must he now travel to reach the base camp?

EASY
IMPORTANT

In a game of lawn chess, where the pieces are moved between the centres of squares that are each 1.00 m on edge, a knight is moved in the following way: 1 two squares forward, one square right ward, 2 two squares leftward, one square forward, 3 two squares forward, one square leftward. What are (a) the magnitude and (b) the angle (relative to “forward”) of the knight's overall displacement for the series of three moves?

EASY
IMPORTANT

In the sum A+B=C, vector A has a magnitude of 12.0 m and is angled 40.0° counter clockwise from the +x direction and vector C has a magnitude of 16.0 m and is angled 20.0° counter clockwise from the -x direction. What are (a) the magnitude and (b) the angle (relative to +x) of B?

HARD
IMPORTANT

Three vectors ab and c, each have a magnitude of 50 m and lie in a xy plane. Their directions relative to the positive direction of the x-axis are 30°195° and 315°, respectively. What is 

(a) the magnitude and the angle of the vector a+b+c?

(b) the magnitude and the angle of a-b+c?

(c) the magnitude and the angle of a fourth vector d, such that a+b-c+d=0?