Centre of Gravity

Q.

On what factors does the position of the center of gravity of a body depend ?

Q.

If the same force is applied on two bodies of different masses, the larger acceleration will be produced in the heavier body.

1. True

2. False

Q.

The point at which the entire weight of a body is assumed to be concentrated is known as ___.

1. centre of torque

2. centre of mass

3. centre of velocity

4. centre of gravity

Q.

What do you understand by the gravitational force of earth and weight?

Q.

The position of the centre of gravity of a body remains unchanged even when the body is deformed.

1. True

2. False

Q.

Locate the centre of gravity for the following rectangle.

1. $(6,12)$

2. $(9,4.5)$

3. $(12,6)$

4. $(4.5,9)$

Q. A vertical conducting ring of radius R falls vertically under gravity in a horizontal magnetic field of magnitude $B_0$. Direction of $B_0$ is perpendicular to the plane of ring. when speed of ring becomes $v$,

1. Points C and D are at same potential.
2. Points A and B are at same potential.
3. Time to gain speed $v$ is more than $\frac{v}{g}$
4. No current flow in ring.

Q.

What is different between mass and weight

Q.

For the given figure, where does the center of mass lie?

1. outside the mass and rod system

2. Closer to mass $m_2$

3. Exactly at the midpoint of the rod

4. Closer to mass $m_1$

Q.

Tightrope walkers use _________ to balance their weight.

1. metallic sphere

2. metallic disc

3. metallic ring

4. long cane

Q. In one frame of reference the distance between two points is $d$, then the distance between the same two points in other frame of reference will be

1. $\frac{d}{2}$
2. $d$
3. $2d$
4. $3d$

Q.

A truck driver can load oil drums into the back of the truck by pushing them up a sloping plank or by lifting them directly. Each drum has a mass of 80 kg, the plank is 3m long and the back of the truck is 0.8m above the ground. How much force would be needed to lift a drum into the truck directly, without using the plank? [Take g =10m/s²]

1. 500 N

2. 600 N

3. 700 N

4. 900 N

5. 800 N

Q.

For an effective center of mass of the system of particles___

1. the reference point is not required

2. only mass is sufficient

3. both masses and their respective distances from the reference point is required

4. only distance from the reference point is sufficient

Q. Why is the mass of a body concentrated at the center of gravity?

Q.

Two bodies A and B have masses in the ratio 9 : 4 and K.E in the ratio 36 : 25. Calculate ratio of their velocities.

1. 4:5

2. 3:5

3. 2:5

4. 3:7

Q. Which of the following is/are true about the centre of gravity? ( Select all that apply )

1. It is the point through which the weight of a body acts.
2. A body can have multiple centres of gravity.
3. The centre of gravity of an object need not always coincide with its geometric centre.
4. A body can be balanced at a single point if it coincides with the centre of gravity..

Q.

Question 1
What do you mean by free fall?

Q.

The center of mass or center of gravity is used___

1. in a uniform gravitational field to represent the unique point in an object or system

2. in a non-uniform gravitational field to represent the unique point in an object or system

3. in a uniform magnetic field to represent the unique point in an object or system

4. in a uniform electric field to represent the unique point in an object or system

Q. If position of $B$ with respect to $P$, is $+2\text{m}$ and position of $C$ with respect to $P$ is $-4\text{m}$. Where $B,P,C$ are the points along $X-$axis, then what will be the position of $B$ with respect to $C$ ?

1. $3\text{m}$
2. $6\text{m}$
3. $-5\text{m}$
4. $-2\text{m}$

Q.

For which of the following objects the centre of gravity(cog) is correctly represented?

1. 

2. 

3. 

4. None of the above

Q. What is the value of electrostatic constant K

Q.

A block of mass 250kg falling at the rate of 10m in 5s is used to lift a load of 5000N by 2m in the same time. Calculate i) VR and ii) MA. Take g = 10m/s²

1. VR = 5 and MA = 2

2. VR = 2 and MA = 20

3. VR = 20 and MA = 5

4. VR = 5 and MA = 4

5. VR = 2 and MA = 5

Q. Why mass is independent of speed

Q.

A square plate of side 4 metre has uniform mass density and is hinged at the midpoint of one of its edge as shown in the figure. What will be the torque due to gravity on it about the hinged point A? (Mass of the plate = $20kg$; g = $10m{s}^2$)

1. 200 N-m

2. 100 N-m

3. 400 N-m

4. 300 N-m

Q.

A block of mass 300kg falling at 160m in 2s is used to lift a load of 900kgf. If the load rises up by 40m in same time then calculate

1. 360000 J and 480000 J

2. 180000 J and 480000 J

3. 480000 J and 180000 J

4. 36000 J and 48000 J

5. 18000 J and 48000 J

Q.

What is the center of gravity of an object?

1. It is the point at which weight is evenly dispersed and all sides are in balance.

2. It is the point at which density is evenly dispersed and all sides are in balance.

3. It is the point at which weight is randomly dispersed and all sides are in balance.

4. It is the point at which weight is evenly dispersed and all sides are not in balance.

Q. A body is more stable if its centre of gravity is closer to the base than when it is further away. State true of false.

1. True
2. False

Q.

A ruler scale is balanced with two fingers, $F_1$ and $F_2$ at a separation 20 cm and 40 cm from the centre of the scale O respectively. If the person balancing the ruler tries to bring his fingers closer to the centre, which finger will slide first?

1. Insufficient data

2. Both simultaneously

3. $F_1$

4. $F_2$

Q. In a movie scene: "Katrina is thrown off a cliff by villains. Salman has to save her but he jumps one second after she falls." He still saves her since his weight is much more than that of Katrina. Assuming that the day was non-windy, it is possible that Salman will save Katrina.

1. False
2. True

Q.

This Question is about Gravitation :-

According to the Newton's law of gravitation Earth's gravitational force is higher on an object of larger mass .why doesn't that object fall down with higher velocity as compared to an object will lower mass?