# IOE Entrance Preparation question & answer

**IOE entrance preparation**

Physics

1. Which one of the following is vector?

i) mass

ii) Force

iii) Work

iv) Power

Ans is ii) the force has both magnitude and direction but others three have magnitude but not direction.

2. Which of the following is vector?

i) Momentum

ii) Time

iii) Pressure

iv) heat

Ans is i) the momentum has both magnitude and direction but others three have magnitude but not direction.

3. Which is scalar?

i) velocity

ii) Elementary area

iii) KE

iv) momentum

Ans is iii) KE ie energy have magnitude only.

4. Which of the following is scalar?

i) Electric potential

ii) velocity gradient

iii) Magnetic intensity

iv) Torque

Ans: ans is i)

Note:

Vector== all intensities, gradients, strength

Scalar=== all potentials, fluxes

5. Angular Momentum is:

i) scalar

ii) polar vector

iii) an axial vector

iv) same as torque

Ans is iii) Vectors associated with the rotation and hence depends upon axis are axial vector and angular have those properties.

6. Electric current is:

i) Scalar

ii) Vector

iii) May be vector or scalar

iv) tensor

Ans is i)Electric current have both direction and magnitude and direction but it is a scalar as it don’t follow vector law.

Note:

– Necessary condition for a physical quantity to be vector is it should have direction where sufficient condition is that it should obey law of vector addition.

7. The resultant of vectors 4 and 10 cant give the resultant:

i) 6

ii) 13

iii) 10

iv) 15

Ans is iv) The resultant of two vector cant be more than their sum and less then their difference. Their sum is 14 and difference is 6. So, the resultant cant be 15.

8. Minimum unequal vectors to give zero resultant in plane is:

i) 4

ii) 3

iii) 2

iv) 5

Ans is ii)

Note: Required vectors to give zero resultant

Collinear2

Coplanar3

Space 4

9. The magnitude of vector product of two vectors is equal to scalar product. Find the angle between them:

i) 0

ii) 30

iii) 45

iv) 90

Ans is iii) ie 45.

Magnitude of vector product= AB sine of angle between them

Scalar product= AB cosine of the angle between the.

When they are equal,

Tangent of the angle between then = 1= 45

10. The magnitude of three sets of vectors are given below. The resultant of which set cant be zero?

i) 10, 10, 10

ii) 10, 10, 20

iii) 10, 20, 20

iv) 10, 20, 40

Ans is iv) To give zero resultant by 3 sets of vectors they should form triangle. Here to be triangle the sum of two small sides should be equal or greater than the largest one.

11. A force of magnitude 20 N has its one rectangular component 12 then other must be:

i) 16

ii) 8

iii) 14

iv) 10

Ans is i) Let that component be Fcos A

Then, FcosA= 12

cosA = 12/20= 3/5

then sinA= 4/5

another component= FsinA= 20* 4/5 16

12. The angle between i+j and k is:

i) 0

ii) 54.74

iii) 75.96

iv) 45

Ans is ii) cosA=1/root3 a= 54.74

13. If A vector= 2i+ 4j- 2K and B vector= 3i- 2j+ nK are perpendicular then find the value of n.

i) 2

ii) -2

iii) 1

iv) -1

Ans is iv)

For two vector to be perpendicular,

Scalar product should be zero, 6-8-2n= 0, n= -1

14. The unit vector along i+j+k is:

i) i+j+k

ii) i+j+k/2

iii) i+j+k/ 2^1/2

iv)i+j+k/ 3^1/2

ans is iv) magnitude= root 3 so, unit vector is i+j+k/ 3^1/2

15. The position vector of the particle is given by r= acoswt i+ asinwt j. Then the velocity of particle is:

i) parallel to position

ii) Perpendicular to position

iii) Directed towards origin

iv) Directed away origin

Now angle is asinwt/ acoswt= tan wt

First derivative of a position is velocity

Velocity= -aw sin wt+ aw cos wt

angle is = aw cos wt/ -aw sin wt= – cot wt= tan (90 + wt)

So answer is ii)

16. In right handed system:

i) i*j= k

ii) i*i= 0

iii) j*j =1

iv) k*i= j

i), ii) and iv) are correct for concept only

i*j= k

j*k= i

k*i= j

j*1= -k

k*j= -i

i*k= -j

i*i= i*I sin0 = 0

j*j= 0

k*k= 0

17. If A vector= 1i+ 2j+3K and B vector= 3i- 2j+ 1K. Find the area of parallelogram from these vectors is square unit:

i)16 root 3

ii) 8 root 3

iii)64

iv)zero

Concept, the magnitude of cross product gives the area of parallelogram.

Just find the cross product of a and b. you will find a vector then find its magnitude.

18. If the vector 2i + 2j is rotated through 45 degree then the vector will be:

i) 2 i

ii) 2j

iii) 2 root 2 j

iv) 4j

Ans is c.

Now the magnitude is 2 root 2 and angle between then is 45 if they are rotated then the magnitude remains constant and they will be collinear.

19. The difference of two unit vector is unit vector then their sum will be:

i) 2

ii) root 2

iii) root 3

iv) 0

20. The sum of two unit vectors is unit vector then their difference will be;

i) 2

ii) root 2

iii) root 3

iv) 0

..Can you think the answers of both 19 and 20 both is root 3 try at home be crazy its physics…..

Stay connected for more

1. If cos3q-cosq = 0, then general values of =

2. Which one of the following may NOT be true for an onto function f:A® B?

a. n(A) ³ n(B)

b. f(A) = B

c. No horizontal line cuts its graph at more than one point

d. No vertical line cuts its graph at more than one point

. For a square matrix A, which of the following is true?

a. |A| = |AT

| b. |A-1| = |A| c. |A-1| = d. A(adj. A) = |A|

Two lines y = mx + c and y = mx + d are on the opposite sides of the origin if

a. c = -d b. c and d are of same signs

c. c and d are of opposite signs d. c = d

9. If the planes x + 2y + kz = 0 and 2x + y – 2z = 0 are at right angles then the value of k

is

a. 4

b. 2

c. -2

d. 1

10. If = 0 then the angles q between is given by

a. cosq = b. cosq = c. cosq = d. none

11. Which of the following pairs of words does not have the same vowel?

a. book-bull b. blood-flood c. gate-gay d. could-cool

12. A mono syllable word in isolation is _______ stressed.

a. never b. always c. often d. sometimes

13. Sporadic means:

a. occasional b. frequency c. continuously d. never ending

14. A short journey for pleasure ______.

a. itinerary b. jaunt c. junta d. stroll

15. She came when _____.

a. it had rained b. it was raining c. it rained d. it has rained

16. Japan ______the country of island.

a. called b. is called

c. seems to be called d. none of these

17. Provided that she was good, she _____attains this position.

a. will attain b. had c. would d. had attained