Gravitation Test

Result

Gravitation Test - 65

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Weekly Quiz Competition

Question 1
1 / -0

A body of mass $$m$$ is raised to a height $$h$$ above the surface of the earth of mass $$M$$ and radius $$R$$ until its gravitational potential energy increases by $$\dfrac{1}{3} mgR$$. The value of $$h$$ is

A
$$\dfrac{R}{3}$$

B
$$\dfrac{R}{2}$$

C
$$\dfrac{mR}{(M + m)}$$

D
$$\dfrac{mR}{M}$$

Solution
Question 2
1 / -0

The value of acceleration due to gravity on Mount Everest is

A
$$g$$

B
$$>g$$

C
$$<g$$

D
$$zero$$

Solution
Question 3
1 / -0

Choose the correct statement:

A
The dimensional formula for $$G$$ is $${M}^{-1}{L}^{3}{T}^{-2}$$

B
$$G$$ is independent of medium

C
$$F=G\cfrac{{m}_{1}{m}_{2}}{{r}^{2}}$$

D
All of the above

Solution
Question 4
1 / -0

The height at which the value of acceleration due to gravity becomes $$50$$% of that at the surface of the earth. ( Radius of the earth=6400 km) is

A
2630

B
2640

C
2650

D
2660

Solution
Question 5
1 / -0

A man weighs $$'W'$$ on the surface of the earth and his weight at a height $$'R'$$ from surface of the earth is ( R is Radius of the earth)

A
$$\cfrac{W}{2}$$

B
$$\cfrac{W}{4}$$

C
$$W$$

D
$$4W$$

Solution
Question 6
1 / -0

If retardation produced by air resistance of air resistance is one - tenth of acceleration due to gravity. the time to reach maximum height.

A
Decrease by 11 percent

B
Increase by 11 percent

C
Decrease by 9 percent

D
Increase by 9 percent

Solution
Question 7
1 / -0

An express train is moving with a velocity $$\mathbf { V } _ { 1 }$$ Its driver finds another train is moving on the same track in the same direction with velocity $$v _ { 2 }$$ s. To escape collision. driver applies retardation a on the train. The minimum time of escaping collision will be

A
$$t = \frac { v _ { 1 } - v _ { 2 } } { a }$$

B
$$t = \frac { v _ { 1 } ^ { 2 } - v _ { 2 } ^ { 2 } } { 2 }$$

C
None

D
Both

Solution

As the trains moving in the same direction so the initial relative speed
$$(V_1-V_2)$$ and by applying retardation final relative speed become zero.
From
$$\begin{array}{l} V=u-at \\ O=\left( { { V_{ 1 } }-{ V_{ 2 } } } \right) -at \\ t=\dfrac { { { V_{ 1 } }-{ V_{ 2 } } } }{ a } \end{array}$$
Question 8
1 / -0

Ratio of gravitational force acting on body at height $$1600\ km$$ to gravitational force acting on the same body on Earth's surface $$(R = 6400\ km)$$.

A
$$5 : 4$$

B
$$15 : 16$$

C
$$4 : 5$$

D
$$16 : 25$$

Solution
Question 9
1 / -0

Kepler's law of area is based on

A
Conservation of linear momentum

B
Conservation of angular mementium

C
Conservation of energy

D
both(1) and |(2)

Solution

Kepler's law of area is based on conservation of angular momentum.
The correct option is B.
Question 10
1 / -0

The gravitational potential energy of an object is due to

A
its mass

B
its acceleration due to gravity

C
its height above the earth surface

D
all of the above

Solution

The gravitational potential energy of an object is given by: $$mgH$$
(where $$m$$ is the mass of an object , $$g$$ is its acceleration due to gravity and $$H$$ is its height above the earth surface).