MCQ - PHYSICS STD 9 Questions - Vidyadip

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15 questions · timed · auto-graded

MCQ 11 Mark

An object falling freely from rest reaches ground in $2 s .$ If acceleration due to gravity is $9.8\ m s ^{-2}$, then the velocity of object on reaching the ground will be

A
$9.8\ m s ^{-1}$
B
$4.9\ m s ^{-1}$
✓
$19.6\ m s ^{-1}$
D
Zero

Answer

Correct option: C.

$19.6\ m s ^{-1}$

An object falling freely from rest reaches ground in $2 s .$ If acceleration due to gravity is $9.8\ m s ^{-2}$, then the velocity of object on reaching the ground will be $19.6\ m s ^{-1}$ METHOD: Given, $u=0\ g=9.8 m / s ^2$ Time $t =2 s$ Let $' v '$ be the velocity of object on reaching the ground. Using the first equation of motion, $v=u+g t$ We get, $v=0+(9.8)(2)$ Or, $v=19.6\ m / s$.

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MCQ 21 Mark

A body is projected vertically upward with an initial velocity $u.$ If acceleartion due to gravity is $g,$ the time for which it remains in air , is :

A
$\frac{u}{g}$
B
$ug$
✓
$\frac{2 u}{g}$
D
$\frac{u}{2 g}$

Answer

Correct option: C.

$\frac{2 u}{g}$

A body is projected vertically upward with an initial velocity $u$. If acceleartion due to gravity is $g$, the time for which it remains in air, is : $\frac{2 u}{g}$
METHOD : Let't' be the time in which the body reaches its maximum height.
Initial velocity $= u$.
Final velocity $($at the highest point$ )=0$.
Acceleration due to gravity $=-g ($negative sign indicates the body is moving against gravity$).$
Using the first equation of motion,
$v = u + gt$
We get,
$0= u - gt$
Or $t = u / g$
Now total time for which the ball remains in air $=$ Time of ascent $+$ Time of descent
Because time of ascent $=$ Time of descent,
Total time taken $=u / g+u / g=2 u / g$

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MCQ 31 Mark

The force of attraction between two masses each of $1\ kg$ kept at a separation of $1 m$ is :

A
$9.8\ N$
B
$6.7\ N$
C
$980\ N$
✓
$6.7 \times 10^{-11}\ N$

Answer

Correct option: D.

$6.7 \times 10^{-11}\ N$

The force of attraction between two masses each of $1\ kg$ kept at a separation of $1\ m$ is $ :6.7 \times 10^{-11}\ N$

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MCQ 41 Mark

The gravitational force between two bodies is :

A
Always repulsive
✓
always attractive
C
attractive only at large distance
D
Repulsive only at large distance .

Answer

Correct option: B.

always attractive

The gravitational force between two bodies is : Always attractive

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MCQ 51 Mark

Action and reaction act on :

A
Same body in opposite directions.
✓
Different bodies in oppposite directions.
C
Different bodies , but in the same direction.
D
Same body in the same direction.

Answer

Correct option: B.

Different bodies in oppposite directions.

Action and reaction act on : Different bodies in opposite directions

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MCQ 61 Mark

Newton's third law :

A
defines the force qualitatively
B
Defines the force quantitatively.
✓
Explains the way the force acts on a body .
D
Gives the direction of force.

Answer

Correct option: C.

Explains the way the force acts on a body .

Newton's third law : Explains the way the force acts on a body.

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MCQ 71 Mark

The acceleration produced in a body by a force of given magnitude depends on

A
size of the body
B
shape of the body
✓
mass of the body
D
none of these

Answer

Correct option: C.

mass of the body

The acceleration produced in a body by a force of given magnitude depends on Mass of the body

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MCQ 81 Mark

The correct form of Newton's second law is :

✓
$F=\frac{\Delta p}{\Delta t}$
B
$F=m \frac{\Delta v}{\Delta t}$
C
$F=v \frac{\Delta m}{\Delta t}$
D
$F = mv$

Answer

Correct option: A.

$F=\frac{\Delta p}{\Delta t}$

The correct form of Newton's second law is : $F =\frac{\Delta p }{\Delta t }$

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MCQ 91 Mark

The unit of linear momentum is :

✓
$N s$
B
$kg\ m s ^{-2}$
C
$N s ^{-1}$
D
$kg ^2\ m s ^{-1}$

Answer

Correct option: A.

$N s$

The unit of linear momentum is $: N s$

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MCQ 101 Mark

The linear momentum of a body of mass m moving with velocity v is

A
$v/m$
B
$m/v$
✓
$mv$
D
$1/mv$

Answer

Correct option: C.

$mv$

The linear momentum of a body of mass m moving with velocity $v$ is $: mv$

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MCQ 111 Mark

A force is needed to :

✓
Change the state of motion or state of rest of the body .
B
Keep the body in motion
C
keep the body stationary
D
keep the velocity of body constant .

Answer

Correct option: A.

Change the state of motion or state of rest of the body .

A force is needed to : Change the state of motion or state of rest of the body.

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MCQ 121 Mark

A tennis ball and a cricket ball , both are stationary. To start motion in them .

A
a less force is required for the cricket ball than for the tennis ball .
✓
a less force is required for the tennis ball than for the cricket ball
C
same force is required for both the balls .
D
nothing can be said .

Answer

Correct option: B.

a less force is required for the tennis ball than for the cricket ball

Less force is required for the tennis ball than for the cricket ball.

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MCQ 131 Mark

The property of inertia is more in :

A
a car
✓
a truck
C
a horse cart
D
a toy car

Answer

Correct option: B.

a truck

The property of inertia is more in a truck .

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MCQ 141 Mark

The non - contact force is :

A
Force of reaction
✓
Force due to gravity
C
Tension in string
D
Force of friction

Answer

Correct option: B.

Force due to gravity

Force due to gravity is a non-contact force.

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MCQ 151 Mark

Which of the following is a contact force:

A
Electrostatic force
B
Gravitational force
✓
Frictional force
D
Magnetic force

Answer

Correct option: C.

Frictional force

Frictional force is a contact force.

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MCQ - PHYSICS STD 9 Questions - Vidyadip