1
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
A force $$\overrightarrow F = \alpha \widehat i + 3\widehat j + 6\widehat k$$ is acting at a point $$\overrightarrow r = 2\widehat i - 6\widehat j - 12\widehat k$$. The value of $$\alpha $$ for which angular momentum about origin is conserved is
A
zero
B
1
C
$$-$$ 1
D
2
2
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
Light of wavelength 500 nm is incifent on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is
A
$$ \ge $$ 2.8 $$ \times $$ 10$$-$$9 m
B
$$ \le $$ 2.8 $$ \times $$ 10$$-$$12 m
C
< 2.8 $$ \times $$ 10$$-$$10 m
D
< 2.8 $$ \times $$ 10$$-$$9 m
3
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth. Then,
A
the linear momentum of S remains constant in magnitude.
B
the acceleration of S is always directed towards the centre of the earth.
C
the angular momentum of S about the centre of the earth changes in direction, but its magnitude remains constant.
D
the total mechanical energy of S varies periodically with time.
4
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
An automobile moves on a road with a speed of 54 km h$$-$$1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is
A
10.86 kg m2 s$$-$$2
B
2.86 kg m2 s$$-$$2
C
6.66 kg m2 s$$-$$2
D
8.58 kg m2 s$$-$$2