8/10/2019 Pt 4 Jee Advanced Sol Eng 09-05-2013

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SOL090513 - 1

PART-I (Physics)

1. Choose the most ................................Ans. (B)

2. A ray of light ................................Sol. (B)

Apply Snell's law on various surfaces one by one :

1 sin 90 = !1sin r1 "sin r1= 2

1" r1= 45

!1cos r1 = !2sin r2 " sin r2 =2

1

!

!2cos r2= !3sin r3 " sin r3 =3

rsin1 22

2 #!

!3cos r3= 1 =3

122#!

sin2r3+ cos2r3= 1

"3

122#!+

3

1= 1 " !2

2 = 3 " !2= 3

3. The circular ..... ...........................Sol. (B)

4. A ball B of mass ................................Sol. (D)

mv1= 2mv2

v2= 2

v1

t = 2/v

x

1=

1v

xd2 %

" 2x = 2d + xx = 2d

& Final distance = d + x = 3d.

5. A long plank ........... .....................Sol. (D)

HINTS & SOLUTIONS

DATE : 09-05-2013 COURSE NAME : REVISION CLASSES

PART TEST-4 (PT-4) JEE ADVANCEDTARGET : JEE (ADVANCED)-2013

Linear momentum conservation '+

2 6

1 2 = (1 + 1 + 2)vv = 2 m/sW

f= k

fk

i

=2

1 4 22

2

1 1 22

2

1 2 62

= 30 J

6. A ball of mass ................................Sol. ( A)

Let ube the velocity of the ballw.r.t. wedge when it reaches the floor.

Then, the x-component of velocity of the ball

w.r.t. ground will be (()

*++,

-#

2

uv towards right.

By momentum conservation :

0 = m(v) + m (()

*++,

-#

2

uv " u = 2 2 v

Therefore, the y-component of velocity of the ball after the

elastic collision with the floor will be u cos 45 =2

u= 2v

(upward)

&Maximum height =g

v2

g2

)v2( 22.

7. Two blocks of ................................Sol. (B)

Work done by spring on the block of mass m1= W

1= change in

kinetic energy

=2

1m

1v

12

2

1m

1(0)2=

2

1m

1v

12

Similarly W2=

2

1m

2v

22

2

1

W

W=

222

211

vm2

1

vm2

1

from conservation of momentumm

1v

1= m

2v

2

&2

1

W

W=

2

1

v

v=

1

2

m

m.

8. Three small ................................Sol. (A)

8/10/2019 Pt 4 Jee Advanced Sol Eng 09-05-2013

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SOL090513 - 2

After the collision between 1 and 2, mass 1 stops and mass 2proceeds to right with speed v

0 to collide with mass 3. The

collision between mass 2 and 3 is perfectly inelastic. Hence 2and 3 also come to rest after the collision.

9. A gun which ................................

Sol. (B)

Force on table due to collision of balls :

Fdynamic

=

dt

dp= 2 20 20 103 5 0.5 = 2 N

Net force on one leg =4

1(2 + 0.2 10) = 1 N

10. A particle is ................................Sol. (D)

Change in momentum = Impulse

kJjJiJP zyx %%./!

= 30(0.1) i +2

1(80) (0.1)j + (50) (0.1) k

= k5j4i3 #%

|P|!

/ = 25 kg .secm

11. Consider an optical ................................

Sol. ( AB)

If 0< 90

If their is no TIR.

90 0 < sin1 ()

*+,

-4

3

0>2

1 sin1

4

3

Similarly if 0> 90

then 0