- Introduction
- |
- Position and Displacement
- |
- Average velocity and speed
- |
- Instantaneous velocity and speed
- |
- Acceleration
- |
- Motion with constant acceleration
- |
- Free fall acceleration
- |
- Relative velocity
- |
- Solved Examples Part 1
- |
- Solved Examples Part 2
- |
- Solved Examples Part 3
- |
- Solved Examples Part 4
- |
- Solved Examples Part 5

- Position Distance and Displacement
- |
- Average velocity and speed
- |
- Velocity and acceleration
- |
- Uniformly accelerated motion
- |
- Relative Velocity
- |
- Kinematics Question 1
- |
- Kinematics Question 2

t

a. t

b. t

c. t

d. Depends on the mass of the body

. Let H be the height

then

First Half

H/2=(1/2)gt

or

(1/2)gt

Also v=gt

Second Half

H/2=vt

or

(H/2)=gt

or

(1/2)gt

From 1 and 2

(1/2)gt

t

or t

or t

t

so t

Hence a is correct

a. 612 m

b. 662 m

c. 630 m

d. 605 m

. Here

v

v

Now x=v

or x=662 m

Hence b is correct

a. 13.6 m

b. 10 m

c. 12.6 m

d. none of these

. Here the nut intially has the velocity of the elevator ,so choosing upward as positive ,v

also a=-g=-9.8 m/s

The time taken to hit the bottom is 2 s so

y=v

=-13.6 m

Hence the bottom of the shaft was 13.6 m below elevator when nut fall off

Hence (a) is correct

a.the speed of the particle decreases when v.a <0

b. the speed of the particle decreases when v.a >0

c.the speed of the particle increases when v.a=0

d. the speed of the particle decreases when |v|<|a|

. when v.a <0

That mean they are in opposite direction

So when the particle is moving towards origin,acceleration is acting outwards so it is decreasing the speed

When the particle is moving outwards,acceleration is acting inwards hence it is decreasing the speed

So this option is correct

When v.a > 0

That means v and a are in same direction

When the particle is moving towards origin, acceleration is also acting inwards so increasing the speed

When the particle is moving outwards,acceleration is also acting outwards hence increasing the speed

So this option is not correct

when v.a=0

Then possible cases are

Acceleration is zero

Velocity is zero

Both are zero

So speed does not increases in all cases.So this option is not correct

When

|v|<|a|

Possible cases

Velocity is positive ,accleration is positive ----Speed increase

Velocity is negative ,acceleration is negative----Speed increase

Velocity is positive,acceleration is negative

Velocity is negative ,acceleration is positive---Speed decreases

So this is not correct option

So correct answer is a

Go Back to Class 11 Maths Home page Go Back to Class 11 Physics Home page

- Principles of Physics Extended (International Student Version) (WSE)
- university physics with modern physics by Hugh D. Young 13th edition
- NCERT Exemplar Problems: Solutions Physics Class 11
- H.C. Verma Concepts of Physics - Vol. 1
- CBSE All in One Physics Class 11 by Arihant
- NCERT Solutions: Physics Class 11th
- New Simplified Physics: A Reference Book for Class 11 (Set of 2 Parts)
- Pradeep's A Text Book of Physics with Value Based Questions - Class XI (Set of 2 Volumes)
- Oswaal CBSE Sample Question Papers For Class 11 Physics (For 2016 Exams)