Two astronauts A and B off mass $$m_a$$ and $$m_b$$ are in space. A pushes B with some force. ($$m_a =m_b$$)

their accelerations are equal in magnitude but opposite in direction

acceleration of A is greater than that of B

acceleration of A is less than that of B

MCQ Questions for Class 8 Physics Force And Pressure Quiz 6

When two forces,applied on an object, equal and opposite,then the forces

0%
May move the object
0%
May stop the object
0%
May move the object and also cause a change in its shape
0%
Do not move the object but may cause a change in its shape.

If two forces act in opposite directions on an object,the net force acting on it is the

0%
Addition of two forces
0%
Difference of two forces
0%
Division of two forces
0%
Multiplication of two forces

Change of shape and size due to force can be seen by applying force on:

0%
a spring
0%
a sponge
0%
an inflated balloon by pressing between the two hands
0%
all of these

Length of a rubber band ________ when a stretching force is applied.

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Increases
0%
Decreases
0%
Remains same
0%
None

If force is applied on the body in the direction of motion then

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Speed of the body will increase
0%
Speed of the body will decrease
0%
Speed of the body will not change at all
0%
All the options are possible

In the game of cricket, the stumps fall when the ball strikes them. This is an example of

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Contact force
0%
Non contact force
0%
Displacement force
0%
None

Identify the type of force in diagram

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Push
0%
Pull
0%
No force is acting
0%
Both A and B

Force can also be defined as

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Mass per unit volume
0%
Distance covered in unit time
0%
External cause which can change the state of motion
0%
None

Force is an external effect in the form of a push or pull, which ..................

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Produces or tries to produce motion in a body at rest
0%
Stops or tries to stop a moving body
0%
Changes or tries to change the direction of motion of the body
0%
None of these

When you and your friend pushed heavy table in the same direction, it becomes easier to move. This is because:

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The net force is the sum of forces.
0%
The net force is the difference of force.
0%
The net force is division of forces.
0%
The net force is multiplication of forces.

Explanation

If two forces act on an object in the same direction, the net force is equal to the sum of the two forces. This always results in a stronger force than either of the individual forces alone.

Hence, the net force is the sum of forces.

$F_{net}=F_1+F_2$

1059172_1165556_ans_8e8b00c284244deabda21101ce9358f5.png

The $SI$ units of Force are _____ or _____.

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$kg \ m/s,\ N$
0%
$kg\ m/s^2, \ Ne$
0%
$kg\ km/hr$ , Newton
0%
$kg\ m/s^2, \ N$

Explanation

F = m a

$F = ma$ ,

So the

S I

$SI$ unit of force =

(S I unit of m) . (S I unit of a) = k g m / s^{2}

$(SI\ \text{unit of }\ m).(SI \ \text{unit of}\ a) = kg \ m/s^2$ or Newton

(N)

$(N)$

Write true or false for each statement:
A force can change the direction of motion of a moving body.

0%
True
0%
False

Which of the following is not an effect of force?

0%
Change in the direction of an object
0%
Change in the shape and size of an object
0%
Change in the mass of an object
0%
Change in the position of a stationary object

What kind of force is used by an archer to pull a bow?

0%
Frictional force
0%
Muscular force
0%
Gravitational force
0%
Magnetic force

Which one of the following forces is a contact force?

0%
Force of gravity
0%
Force of friction
0%
Magnetic force
0%
Electrostatic force

A brick is kept in three different ways on a table as shown in Figure. The pressure exerted by the brick on the table will be

0%
maximum in position A
0%
maximum in position B
0%
maximum in position C
0%
equal in all cases.

Explanation

P = \frac{F}{A}

$P = \frac{F}{A}$

F = m g

$F= mg$ is same in all the cases
P will maximum when Area (A) is minimum.

Which is much easier to burst an inflated balloon. When the same force is applied

0%
Needle
0%
Finger
0%
Both are the same
0%
Can't say

Explanation

Pressure =

\frac{F o r c e}{A r e a}

$\dfrac{Force}{Area}$ ,

It means lesser the area more the pressure.

Now, if we apply the same force by needle and by finger, more pressure will be applied on the inflated balloon in case of the needle as the needle has less area of contact than the finger.

During dry weather, while combing hair, sometimes we experience hair flying apart. The force responsible for this is

0%
force of gravity.
0%
electrostatic force.
0%
force of friction.
0%
magnetic force.

Explanation

When two objects are rubbed together, there is exchange of electrons.

During dry weather, the hair follicles are straightened up and they have picked up electrons during the rubbing process. The follicles have the like charges that repel each each other.

The force responsible for this is the

electrostatic force

$\text{electrostatic force}$ .

Given figure shows a man with a parachute. Name the force which is responsible for his downward motion. Will he come down with the same speed without the parachute?

0%
Force of gravity, No
0%
Air resistance, No
0%
Air resistance, Yes
0%
Force of gravity, Yes

While sieving grains, small pieces fall down. Which force pulls them down?

0%
Coulomb force
0%
Gravitational force
0%
Nuclear force
0%
Electrostatic force

A girl stands on a box having 60 cm length, 40 cm breadth and 20 cm width in three ways. The pressure exerted by the box will be:

0%
maximum when length and breadth form the base
0%
maximum when breadth and width form the base
0%
maximum when width and length form the base
0%
the same in all the above three cases

Explanation

The force exerted by the box on base=Weight of object=

W

$W$

The pressure that it exerts on the base

= \frac{W}{A}

$=\dfrac{W}{A}$

where

A

$A$ is the area of the base.

Hence the pressure is maximum for smallest area of the base, which is when formed by breadth and width.

A knife with sharp edge is more effective than a blunt knife because:

0%
the pressure increases due to decrease in surface area of contact.
0%
the force increases due to decrease in surface area of contact.
0%
it's velocity ratio decreases.
0%
it gets blunt due to long use.

What is the impact of balanced forces on an initially stationary object?

0%
The object remains at rest
0%
The object moves with uniform speed
0%
The object moves in the direction of frictional force acting on it
0%
The object moves in a direction perpendicular to the surface of contact

The state of rest or state of motion of a body can be changed by using

0%
Pressure
0%
Force
0%
Heat
0%
None of these

Two astronauts A and B off mass

m_{a}

$m_a$ and

m_{b}

$m_b$ are in space. A pushes B with some force. (

m_{a} = m_{b}

$m_a =m_b$ )

0%
acceleration of A is greater than that of B
0%
acceleration of A is less than that of B
0%
neither is accelerated
0%
their accelerations are equal in magnitude but opposite in direction

Explanation

A pushes B with some force, then by newton's third law same force will be applied by B on A, now since mass of both the astronaut are same,as

F = m a

$F=ma$

As mass is same and just direction of force is opposote, so acceleration will be equal in magnitude but opposite in direction.

Which of the following is/are true about force

0%
Force will always change the magnitude of velocity
0%
Force will always change the direction of velocity
0%
S.I unit of force is Newton
0%
All the above.

Which force is used by an archer to pull a bow?

0%
Muscular force
0%
Frictional force
0%
Gravitational force
0%
Elastic spring force

Which of the following requires a pushing force?

0%
Throwing a stone at a bird.
0%
Grabbing hold of a pencil.
0%
Leaves falling from a tree.
0%
A load lifted by a pulley.

Which of the following units is used to measure thrust?

0%
Dyne
0%
Pascal
0%
Newton per meter square
0%
Dyne per centimeter

Animals like camels walk easily in deserts as broad feet exert less pressure on sandy ground.

0%
True
0%
False

Explanation

Pressure = \frac{T h r u s t}{A r e a}

$\text{Pressure}=\dfrac{Thrust}{Area}$

Pressure is inversely proportional to the area of the contact. As camels have broad feet, these imply a larger area of contact so the pressure exerted by camels' feet on the sandy ground would be less .

Hence option (A) is correct .

CBSE Questions for Class 8 Physics Force And Pressure Quiz 6 - MCQExams.com

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Practice Class 8 Physics Quiz Questions and Answers

CBSE Questions for Class 8 Physics Force And Pressure Quiz 6 - MCQExams.com

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Practice Class 8 Physics Quiz Questions and Answers

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