1
COMEDK 2021
MCQ (Single Correct Answer)
+1
-0

When a car of mass $$m$$ is moving with speed $$v$$ along a circle of radius $$r$$ on a level road, the centripetal force is provided by $$f$$, where $$f$$ denotes

($$\mu_s$$ $$\to$$ coefficient of friction, N $$\to$$ normal reaction)

A
$${{m{v^2}} \over r} = f \le {\mu _s}N$$
B
$$f < {\mu _s} = {{m{v^2}} \over r}$$
C
$$f = {\mu _s}N = {{m{v^2}} \over r}$$
D
$$f = {\mu _k}N = {{m{v^2}} \over r}$$
2
COMEDK 2021
MCQ (Single Correct Answer)
+1
-0

Ba-122 has half-life of 2 min. Experiment has to be done using Ba-122 and it takes 10 min to set up the experiment. It initially 80 g at Ba-122 was taken, how much Ba was left when experiment was started?

A
2.5 g
B
5 g
C
10 g
D
20 g
3
COMEDK 2021
MCQ (Single Correct Answer)
+1
-0

When the speed of light becomes $$\frac{2}{3}$$ of its present value, then the energy released in a given atomic explosion would

A
decrease by a factor $$\frac{2}{3}$$
B
decrease by a factor $$\frac{4}{9}$$
C
decrease by a factor $$\frac{5}{9}$$
D
decrease by a factor $$\frac{\sqrt5}{9}$$
4
COMEDK 2021
MCQ (Single Correct Answer)
+1
-0

What should be the value of self-inductance of an inductor that should be connected to 220 V 50 Hz supply, so that a maximum current of 0.9 A flows through it?

A
11 H
B
2 H
C
1.1 H
D
5 H
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