9th Class Physics Force and laws of motion Question Bank

done Force and Laws of Motion

• A) Must act on same body

B) Must act on different bodies need not be equal in magnitude but must have

C) The same line of action

D) Must be equal in magnitude but need not have the same line of action

• A) Cover greater distance

B) Maintain momentum conservation

C) Gain energy by running

D) Gain momentum

• A) Its mass will change

B) Its weight will change, but not mass

C) Both mass and weight will change

D) Its mass and weight will remain the same

• A) $\sqrt{{{w}_{1}}{{w}_{2}}}$

B) $\frac{{{w}_{1}}+{{w}_{2}}}{2}$

C) $\left( \frac{{{w}_{1}}^{2}+{{w}_{2}}^{2}}{2} \right)$

D) $\sqrt{{{w}_{1}}^{2}+{{w}^{2}}_{2}}$

• A) 1 N

B) 9.8 N

C) 980 dyne

D) None of these

• A) At the centre of the earth

B) During a free fall

C) In interplanetary space

D) On a frictionless surface

• A) Relative density

B) Density

C) Pressure

D) Thrust

• A) $\frac{\sqrt{\upsilon }}{\sqrt{2}}$

B) $\frac{\upsilon }{2}$

C) $\frac{\upsilon }{\sqrt{2}}$

D) None of these

• A) 0.336 N

B) 0.294 N

C) 683N

D) 0.392 N

• A) $\text{4}.\text{9 m}/{{\text{s}}^{\text{2}}}$

B) $\text{2}.\text{94 m}/{{\text{s}}^{\text{2}}}$

C) $\text{1}.\text{4 m}/{{\text{s}}^{\text{2}}}$

D) $\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}$

• A) Roughly equal

B) Unequal

C) Exactly equal

D) In the inverse ratio of their diameters

• A) Move away from the shore

B) Remain stationary

C) Move towards the shore

D) Sink

• A) Equal to zero

B) Equal to the force exerted by B on A

C) Greater than the force exerted by B on A

D) Less than the force exerted by B on A

• A) Acceleration of A is greater than that of B

B) Acceleration of A is less than that of B

C) Neither is accelerated

D) Their accelerations are equal in magnitude but opposite in direction

• A) Zero

B) 12 Newton

C) 1.2 Newton

D) 0.12 Newton

• A) $\frac{\sqrt{2}}{3}$

B) $\frac{\sqrt{3}}{2}$

C) 0.5

D) 1.0

• A) $2w$

B) 3 $w$

C) 4 $w$

D) 5 $w$

• A) 6 m/s

B) 8 m/s

C) 9 m/s

D) 11 m/s

• A) $\frac{AB}{A+C}$

B) $\frac{A+C}{B+C}$

C) $\frac{AC}{B+C}$

D) $\frac{A+B}{AC}$

• A) 49 cm/sec

B) 147 cm/sec

C) 98 cm/sec

D) 196 cm/sec

• A) Zero

B) 13 N

C) 3.3 M

D) 19.6 N

• A) $2u\cos \theta$

B) $u\cos \theta$

C) $\frac{2u}{\cos \theta }$

D) $\frac{u}{\cos \theta }$

• A) 10 m/s

B) 20 m/s

C) $10\sqrt{2}\,\,m/s$

D) $20\sqrt{2}\,\,m/s$

• A) $\left( \frac{{{m}_{1}}-{{m}_{2}}}{{{m}_{1}}+{{m}_{2}}} \right)g$

B) ${{\left( \frac{{{m}_{1}}-{{m}_{2}}}{{{m}_{1}}+{{m}_{2}}} \right)}^{2}}g$

C) $\frac{{{m}_{2}}g}{{{m}_{1}}+{{m}_{2}}}$

D) $\frac{{{m}_{1}}g}{{{m}_{1}}+{{m}_{2}}}$

• A) $\sqrt{\frac{h}{g}{{\left( \frac{{{m}_{2}}+{{m}_{2}}}{{{m}_{2}}-{{m}_{2}}} \right)}^{2}}}$

B) $\sqrt{\frac{h}{g}\left( \frac{{{m}_{1}}+{{m}_{2}}}{{{m}_{1}}-{{m}_{2}}} \right)}$

C) $\sqrt{\frac{2h}{g}\left( \frac{{{m}_{2}}+{{m}_{2}}}{{{m}_{2}}-{{m}_{2}}} \right)}$

D) $\sqrt{\frac{h}{2g}\left( \frac{{{m}_{2}}+{{m}_{2}}}{{{m}_{2}}-{{m}_{2}}} \right)}$

• A) $\frac{Mn}{60}$

B) $60\,mn$

C) $\frac{M}{60\,n}$

D) $\frac{n}{60M}$

• A) Resultant would be zero

B) Body would not move at all

C) Both [a] and [b]

D) None of these

• A) $0.\text{98 m}/{{\text{s}}^{\text{2}}}$

B) $\text{1}.\text{47 m}/{{\text{s}}^{\text{2}}}$

C) $\text{1}.\text{52 m}/{{\text{s}}^{\text{2}}}$

D) $\text{6}.\text{1 m}/{{\text{s}}^{\text{2}}}$

• A) 4 metres

B) 8 metres

C) 16 metres

D) 32 metres

• A) $3\,v\,\cos \,\theta$

B) $2\,v\,\cos \,\theta$

C) $\frac{3}{2}\,v\,\cos \,\theta$

D) $\frac{\sqrt{3}}{2}\,v\,\cos \,\theta$

• A) Below the stone

B) At the point P itself

C) From above the stone

D) Nothing can be decided

• A) Below the stone

B) At the point P itself

C) Above the stone

D) Nothing can be decided

• A) Torque

B) Moment of force

C) Momentm

D) Moment of momentum

• A) Weight

B) Mass

C) Quantity of motion

D) Velocity

• A) Impulse

B) Torque

C) Moment of momentum

D) Couple

• A) $\frac{2m\upsilon }{t}$

B) $\frac{2m(\upsilon +u)}{t}$

C) $\frac{2m(\upsilon +2u)}{t}$

D) $\frac{m(\upsilon +2u)}{t}$

• A)

B) $\tan \theta$

C) $\cot \theta$

D) $\text{cosec }\theta$

• A) $\text{1 m}/{{\text{s}}^{\text{2}}}$

B) $\text{2 m}/{{\text{s}}^{\text{2}}}$

C) $\text{4 m}/{{\text{s}}^{\text{2}}}$

D) $\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}$

• A) A has applied more force

B) B has applied more force

C) A and B both have applied same force

D) None has applied any force

• A) First law

B) Second law

C) Third law

D) None of these

• A) 3200 N

B) 5400 N

C) 6500 N

D) 7800 N

• A) 0.1

B) 0.7

C) 5

D) 10

• A) 2 % of R

B) 3 % of R

C) 4 % of R

D) 5 % of R

• A) Absence of friction

B) absence of inertia

C) More inertia

D) more friction

• A) First law

B) Second law

C) Third law

D) None of these

• A) Are always balanced

B) Are never balanced

C) May or may not be balanced

D) None of these

• A) $\text{2}.\text{5 m}/{{\text{s}}^{\text{2}}}$

B) $0.\text{25 m}/{{\text{s}}^{\text{2}}}$

C) $\text{5 m}/{{\text{s}}^{\text{2}}}$

D) $0.\text{5 m}/{{\text{s}}^{\text{2}}}$

• A) $\text{28}.\text{7 m}/{{\text{s}}^{\text{2}}}$

B) $\text{34}.\text{9 m}/{{\text{s}}^{\text{2}}}$

C) $\text{39}.\text{4 m}/{{\text{s}}^{\text{2}}}$

D) $\text{27}.\text{8 m}/{{\text{s}}^{\text{2}}}$

• A) 22.2 m/s

B) 37.6 kg/sec

C) 58.8 kg/sec

D) None of these

• A) Attraction between them

B) Repulsion between them

C) Some adhesive forces between them

D) Irregularities on the surfaces

• A) $\text{4}.\text{5 x 1}{{0}^{\text{6}}}\text{ N}$

B) $\text{5}.\text{5 x 1}{{0}^{\text{6}}}\text{ N}$

C) $\text{3}.\text{5 x 1}{{0}^{\text{6}}}\text{ N}$

D) $\text{6}.\text{72 x 1}{{0}^{\text{6}}}\text{ N}$

• A) There is no force acting on it

B) The forces acting on it are not in contact with it

C) The combination of force acting on it balance each other

D) The body in vacuum

• A) The body is definitely at rest

B) The body is definitely in the state of uniform motion

C) The body will be either at rest or in the state or uniform motion

D) None of these

• A) Unity

B) zero

C) Infinite

D) none of these

• A) Dyne

B) gram-weight

C) Newton

D) None of these

• A) 980 gwt

B) $\frac{1}{980}kg$ gwt

C) 980 kg wt

D) none of these

• A) Acceleration

B) velocity

C) Speed

D) momentum

• A) Velocity

B) impulse

C) Momentum

D) none of these

• A) Speed of 1 $\text{m}{{\text{s}}^{\text{-1}}}$

B) Acceleration of 1 $\text{m}{{\text{s}}^{\text{-2}}}$

C) Speed of 1 k $\text{m}{{\text{s}}^{\text{-1}}}$

D) None of these

• A) Outward pull on them

B) Inertia

C) Change in momentum

D) Change in acceleration

• A) Force on the object

B) Velocity of the object

C) Mass of the object

D) Inertia of the object

• A) Impulse

B) force

C) Angular velocity

D) none of these

• A) Magnitude

B) Direction

C) Both magnitude and direction

D) Neither magnitude nor direction

B) Necessary evil

C) Important force in daily life

D) All of these

• A) less than

B) equal to

C) Greater than

D) none of these

• A) Conservation of energy

B) Backward thrust of gases produced

C) Newton's first law of motion

D) Newton's third law of motion

• A) $W\left( 1+\frac{a}{g} \right)$

B) $W\left( 1-\frac{a}{g} \right)$

C) $W\left( 1-\frac{{{a}^{2}}}{{{g}^{2}}} \right)$

D) none of these

• A) $\text{1}{{0}^{-\text{3}}}\text{ kg}{{\text{m}}^{-\text{3}}}$

B) $\text{1}{{0}^{-2}}\text{ kg}{{\text{m}}^{-\text{3}}}$

C) $\text{1}{{0}^{2}}\text{ kg}{{\text{m}}^{-\text{3}}}$

D) $\text{1}{{0}^{3}}\text{ kg}{{\text{m}}^{-\text{3}}}$

• A) Zero

B) MV

C) 2 MV

D) $-2MV$

• A) $mng$

B) $mn\upsilon$

C) $mn\upsilon g$

D) $\frac{mn\upsilon }{g}$

• A) Depth of a liquid

B) Density of liquid

C) Colour of a liquid

D) None of these

• A) $\sin \,\theta$

B) $\cos \,\theta$

C) $g$

D) $\tan \,\theta$

• A) ${{\mu }_{\kappa }}<{{\mu }_{s}}$

B) ${{\mu }_{s}}<{{\mu }_{\kappa }}$

C) ${{\mu }_{\kappa }}={{\mu }_{s}}$

D) ${{\mu }_{s}}\le {{\mu }_{\kappa }}$

• A) Static friction

B) kinetic friction

C) Fluid friction

D) sliding friction

• A) $\mu =\sin \theta$

B) $\mu =\cos \theta$

C) $\mu =\tan \theta$

D) None of these

• A) Is independent of velocity

B) Increases with velocity

C) Decreases with velocity

D) None of these

• A) $\text{1}{{0}^{\text{3}}}$

B) $\text{1}{{0}^{\text{2}}}$

C) $\text{1}{{0}^{-\text{2}}}$

D) $\text{1}{{0}^{-\text{3}}}$

• A) is independent of velocity

B) Varies with velocity

C) Increases with velocity

D) Decreases with velocity

• A) Molecular force

B) Decrease in surface area

C) Decrease in irregularities

D) Increase in area

• A) Both inertia and force

B) Only inertia

C) Only force

D) Nothing

• A) Inertia

B) momentum

C) Impulse

D) force

• A) Forward

B) Backward

C) To right side

D) To left side

• A) He cannot lift on the chair

B) He can lift easily

C) He can lift himself but very little

D) None of the above

• A) He cannot do it

B) He can do it easily

C) He can do it but with difficulty

D) None of the above

• A) Gravity

B) Atmosphere

C) Gravity and atmosphere

D) Gases ejected from behind

• A) Equal, opposite and acting on the same body

B) Equal, in the same direction and acting on same body

C) Equal, opposite and acting on different bodies

D) Equal, in same direction and acting on different bodies.

• A) When the vector sum of all the forces acting on the body is zero.

B) When a body is very heavy

C) When the body is very light

D) When the body is a point body

• A) $8\,N$

B) $ON$

C) $2\,\times \,10{{\,}^{4}}\,N$

D) $\frac{1}{2}N$

• A) 0.5 Ns

B) 50 Ns

C) 5 Ns

D) 1 Ns

• A) V

B) 2v

C) Zero

D) $\frac{\upsilon }{2}$

• A) particle going on the circle

B) Particle going along a straight line

C) Momentum of the particle constant

D) Acceleration of the particle constant

• A) $\frac{b}{c+b}$

B) $\frac{a+b}{c}a$

C) $\frac{a}{a+c}a$

D) $\frac{a+c}{a}b$

• A) 15 N

B) 20 N

C) 25 N

D) 30 N

• A) $\text{1}\text{.5 m}/{{\text{s}}^{\text{2}}}$

B) $\text{1}\text{.8 m}/{{\text{s}}^{\text{2}}}$

C) $\text{2}\text{.2 m}/{{\text{s}}^{\text{2}}}$

D) $\text{2}\text{.5 m}/{{\text{s}}^{\text{2}}}$

• A) $\text{9}\text{.8},\text{9}\text{.8}$

B) $\text{4}\text{.9},\text{9}\text{.8}$

C) $\text{9}\text{.8},\text{4}\text{.9}$

D) $\text{4}\text{.9},\text{4}\text{.9}$

• A) $mg$

B) $2m$

C) $\frac{mg}{2}$

D) Zero

• A) 69 N upwards

B) 69 N downwards

C) 29 N upwards

D) 29 N downwards

• A) It has mass

B) It suffers friction

C) It has inertia of rest

D) It has momentum

• A) 5 s

B) 10 s

C) 15 s

D) 20 s

• A) $\frac{a}{a+g}M$

B) $\frac{g}{a+g}M$

C) $\frac{2a}{a+g}M$

D) $\frac{2g}{a+g}M$

• A) $\frac{{{m}_{1}}}{{{m}_{2}}}F$

B) $\frac{{{m}_{2}}}{{{m}_{1}}}F$

C) $\frac{{{m}_{1}}F}{{{m}_{1}}+{{m}_{2}}}$

D) $\frac{{{m}_{2}}F}{{{m}_{1}}+{{m}_{2}}}$

• A) 1N

B) 4N

C) 7N

D) 9N

E) None of these

• A) Zero

B) $\frac{g}{3}$

C) $\frac{2g}{3}$

D) $g$

• A) 0.98 m/s

B) 9.8 m/s

C) 1.96 m/s

D) 19.6 m/s

• A) Climbs up with a uniform speed of 5 m/s

B) Climbs up with an acceleration of $\text{6 m}/{{\text{s}}^{\text{2}}}$

C) Climbs down with an acceleration of $\text{4 m}/{{\text{s}}^{\text{2}}}$

D) Climbs down with a uniform speed of $\text{5 m}/\text{s}$

• A) $\frac{g}{2\sqrt{2}}$

B) $\frac{g}{\sqrt{2}}$

C) $\frac{3g}{2\sqrt{2}}$

D) $\frac{g}{2}$

• A) 3/5

B) 3/4

C) 4/5

D) 2/3

• A) 30 N

B) 40 N

C) 60 N

D) 120 N

• A) Only $\phi$is more than the angle of friction

B) Only $\phi$ is less than the angle of friction

C) Only $\phi$ is equal to the angle of friction

D) For all values of $\phi$

• A) 1N

B) 0.5 N

C) 0.98 N

D) 1.96 N

• A) $m\left( 1-\frac{a}{g} \right)$

B) $\left( 1+\frac{a}{g} \right)$

C) $m$

D) Zero

• A) $\frac{{{S}_{1}}}{{{S}_{2}}}=\frac{{{m}_{2}}}{{{m}_{1}}}$

B) $\frac{{{S}_{1}}}{{{S}_{2}}}=\frac{{{m}_{1}}}{{{m}_{2}}}$

C) $\frac{{{S}_{1}}}{{{S}_{2}}}={{\left( \frac{{{m}_{2}}}{{{m}_{1}}} \right)}^{2}}$

D) $\frac{{{S}_{1}}}{{{S}_{2}}}=-{{\left( \frac{{{m}_{2}}}{{{m}_{1}}} \right)}^{2}}$

• A) The momentum of the system is less than $\text{2}\,\text{kg}\,\text{m}{{\text{s}}^{-\text{1}}}$9

B) The kinetic energy of the system is$\frac{2}{3}J$

C) The kinetic energy of the system is $2J$

D) None of these

• A) $\left( 1+\frac{{{m}_{1}}}{{{m}_{2}}} \right)\sqrt{gh}$

B) $\frac{{{m}_{1}}}{{{m}_{2}}}\sqrt{2gh}$

C) $\left( 1+\frac{{{m}_{1}}}{{{m}_{2}}} \right)\sqrt{2gh}$

D) $\left( 1+\frac{{{m}_{2}}}{{{m}_{1}}} \right)\sqrt{2gh}$

• A) 2 F

B) F

C) $\frac{F}{2}$

D) $\sqrt{2}F$

• A) 20 dynes

B) 20 Newtons

C) 20 kg wt

D) 10 Newtons

• A) 3 cm

B) 2 cm

C) 1cm

D) 0.5cm

• A) $1.7\times \sqrt{2}\times \frac{1}{\sqrt{3}}N$

B) $1.7\times \sqrt{3}\times \frac{1}{2}N$

C) $1.7\times \sqrt{3}N$

D) $1.7\times \sqrt{2}\times \frac{\sqrt{2}}{\sqrt{3}}N$

• A) Striking of two glass balls

B) A bullet striking a bag of sand

C) An electron captured by a proton

D) A man jumping into a moving cart

• A) 50.2 kgf

B) 25.5 kgf

C) 75.0 kgf

D) 42.3 kgf

• A) Truck

B) Car

C) Both simultaneously

D) Data not sufficient

• A) 5 m

B) 4.8 m

C) 3.2m

D) 3.0 m

• A) $2\,\,a{{\upsilon }^{2\,\,}}\,p\,\,\cos \,\theta$

B) $a{{\upsilon }^{2\,\,}}\,p\,\,\cos \,\theta$

C) $2\,\,\,a\upsilon \,\,p\,\,\cos \,\theta$

D) $a\upsilon \,\,p\,\,\cos \,\theta$

• A) $\text{1}0\text{ g dyne c}{{\text{m}}^{\text{-2}}}$

B) $\text{2 dyne c}{{\text{m}}^{\text{-2}}}$

C) $\text{4}0\text{ g dyne c}{{\text{m}}^{\text{-2}}}$

D) $\text{45 g dyne c}{{\text{m}}^{\text{-2}}}$

• A) $\frac{g+a}{3}$

B) $\frac{g-a}{3}$

C) $\frac{4m(g+a)}{3}$

D) $\frac{m(g-a)}{3}$

• A) 12.55 m/sec

B) 17 m/sec

C) 19 m/sec

D) 25 m/sec

• A) 0.2

B) 0.4

C) 0.65

D) 0.75

• A) 10 N, 20 N

B) 20 N, 20 N

C) 10 N, 50 N

D) 10 N, 30 N

• A) $\text{2}.\text{4 x 1}{{0}^{\text{5}}}\text{ m}/\text{sec}$

B) $0.\text{24 x 1}{{0}^{\text{5}}}\text{ m}/\text{sec}$

C) $\text{24 x 1}{{0}^{\text{5}}}\text{ m}/\text{sec}$

D) $\text{245 x 1}{{0}^{\text{5}}}\text{ m}/\text{sec}$

• A) 32

B) 80

C) 106

D) 980

• A) 840 Newton

B) 480 Newton

C) 804 Newton

D) 408 Newton

• A) Same body in opposite directions

B) Same body in the same direction

C) Different bodies in opposite directions

D) Different bodies but in the same direction

• A) $\sqrt{\frac{\upsilon m}{k}}$

B) $\sqrt{\frac{\upsilon k}{m}}$

C) $u\sqrt{\frac{k}{m}}$

D) $u\sqrt{\frac{m}{k}}$

• A) The friction is reduced

B) The mass becomes smaller

C) Only a part of weight has to be overcome

D) g becomes smaller.

• A) 40 N

B) 20 N

C) 4N

D) 2 N

• A) $(M+m)({{\mu }_{1}}+{{\mu }_{2}})g$

B) $(M-m)({{\mu }_{1}}+{{\mu }_{2}})g$

C) $(M+m)({{\mu }_{1}}-{{\mu }_{2}})g$

D) $(M-m)({{\mu }_{1}}-{{\mu }_{2}})g$

• A) When ${{m}_{1}}<{{m}_{2}}$ and ${{m}_{2}}$ at rest, there will be maximum transfer of momentum.

B) When ${{m}_{1}}={{m}_{2}}$ and ${{m}_{2}}$ at rest, there will be maximum transfer of K.E.

C) When collision is oblique and ${{m}_{2}}$ at rest with ${{m}_{1}}={{m}_{2}}$, after collision the ball moves in opposite direction.

D) None of these

• A) In the hand of his brother.

B) Slightly away from the hands of his brother in the direction of motion of the train.

C) Slightly away from the hands of his brother in the direction opposite to the direction of motion of the train.

D) None of the above.

• A) 2000 N

B) 0 N

C) 1000N

D) 500N

• A) $\left( \frac{F}{M} \right)-a$

B) $a$

C) $-a$

D) $\left( \frac{F}{M} \right)$

• A) 2.8 N

B) 8N

C) 2N

D) Zero

• A) $\sin \,\,\theta$

B) $\cos \,\,\theta$

C) $g$

D) $\tan \,\,\theta$

• A) $0.\text{98 m}/{{\text{s}}^{\text{2}}}$

B) $\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}$

C) $0.\text{54 m}/{{\text{s}}^{\text{2}}}$

D) $\text{5}.\text{292 m}/{{\text{s}}^{\text{2}}}$

• A) $\frac{W\,\cos \phi }{\cos \,(\theta -\phi )}$

B) $\frac{W\,\sin \phi }{\cos \,(\theta -\phi )}$

C) $\frac{W\,\tan \phi }{\sin (\theta -\phi )}$

D) $\frac{W\,\sin \phi }{g\sin (\theta -\phi )}$

E) None of these

• A) $\mu \,mg$

B) $\mu \,\left[ mg-\left( \frac{\sqrt{3}}{2} \right)F \right]$

C) $\mu \,\left[ mg-\left( \frac{F}{2} \right) \right]$

D) $\mu \,\left[ mg+\left( \frac{F}{2} \right) \right]$

• A) 2.5 N

B) 0.98 N

C) 4.9 N

D) 0.49 N

• A) Both parts continue to move in the same direction as that of the original body.

B) One part comes to rest and the other moves in the same direction as that of the original body.

C) One part comes to rest and the other moves in the direction opposite to that of the original body.

D) one part moves in the same direction and the other in the direction opposite to that of the original body.

• A) One ball from the right end will move on with speed $\varepsilon \upsilon$, all the other remains at rest

B) Two balls from the extreme right will move on the speed u each and the remaining balls will be at rest.

C) All the balls will start moving to the right with.

D) All the six balls originally at rest will moves on with speed $\frac{\upsilon }{6}$ each and the two incident ball will come to rest.

• A) 0 and 25

B) 5 and 20

C) 10 and 15

D) 20 and 5

• A) He exerts on the wagon

B) The wagon exerts on him

C) The ground exerts on him

D) He exerts on the ground.

• A) W

B) 2W

C) 3W

D) 4W

• A) g

B) $\frac{3g}{4}$

C) $\frac{g}{4}$

D) $\frac{g}{2}$

• A) $\frac{{{V}_{0}}^{2}}{2\mu g}$

B) $\left( \frac{{{V}_{0}}^{2}}{\mu g} \right)$

C) $\frac{{{V}_{0}}}{\mu g}$

D) $\frac{{{V}_{0}}^{2}}{\mu g}$

• A) 800 N

B) (6) 1000 N

C) 1200 N

D) 2400 N

E) None of these

• A) $\frac{1-e}{1+e}$

B) $\frac{1+e}{1-e}$

C) $\frac{e-1}{1-e}$

D) $\frac{e-1}{1+e}$

• A) $90{}^\circ$
B) $0{}^\circ$
C) $180{}^\circ$
D) $30{}^\circ$