Quiz about Mechanics Revision Multiple Choice

Question 1

In the equation $$F_r=\mu R$$

the symbol $$R$$ represents

Accepted Answer

Normal Reaction force

Answer

Resultant force

Answer

Resistance

Answer

Coefficient of friction

Answer

Frictional force

Question 2

The equation $$speed=\frac{dis an ce}{time}$$ is

Accepted Answer

True as long as the object has zero acceleration

Answer

Always true

Answer

Never true

Answer

True as long as the object has constant acceleration

Answer

True as long as the object has zero velocity

Question 3

The equation $$v=u+at$$ is

Accepted Answer

True as long as the object has constant acceleration

Answer

Always true

Answer

Never true

Answer

True as long as the object has zero acceleration

Answer

True as long as the object has zero velocity

Question 4

A particle is projected on a horizontal plane with a speed of $$u$$ and at an angle $$\alpha$$ to the plane.

Which one of the following statements is NOT true at the point when the particle strikes the plane?

Accepted Answer

Vertical velocity is $$u\sin(\alpha)$$

Answer

Horizontal velocity is $$u\cos(\alpha)$$

Answer

Speed is $$u$$

Answer

Speed is at its maximum

Answer

Horizontal acceleration is zero

Question 5

A particle is projected on a horizontal plane with a speed of $$u$$ and at an angle $$\alpha$$ to the plane.

Which one of the following statements is NOT true at the point when the particle strikes the plane?

Accepted Answer

Vertical acceleration is zero

Answer

Vertical acceleration is $$-g$$

Answer

Horizontal displacement is called the range

Answer

Vertical displacement is zero

Answer

Vertical velocity is $$-u\sin(\alpha)$$

Question 6

A particle is projected on a horizontal plane with a speed of $$u$$ and at an angle $$\alpha$$ to the plane.

Which one of the following statements is NOT true at the highest point in the flight?

Accepted Answer

Vertical acceleration is zero

Answer

Vertical velocity is zero

Answer

Horizontal velocity is $$u\cos(\alpha)$$

Answer

Horizontal displacement is half of the range

Answer

Speed is at its minimum

Question 7

A particle is projected on a horizontal plane with a speed of $$u$$ and at an angle $$\alpha$$ to the plane.

Which one of the following statements is IS true at the highest point in the flight?

Accepted Answer

Time to this point is half the total time of flight

Answer

Horizontal acceleration is $$g$$

Answer

Vertical displacement is zero

Answer

Displacement is half the final displacement

Answer

Speed is at its maximum

Question 8

On a velocity/time graph, which one of the following is NOT true?

Accepted Answer

a straight line indicates constant velocity

Answer

the acceleration is given by the gradient

Answer

the distance travelled is given by the area between the curve or line and the $$t$$ axis

Answer

a line with a negative gradient indicates a retardation or deceleration

Answer

If the line is curved not straight then acceleration is not constant

Question 9

The vectors $$ai+bj$$ and $$ci+dj$$ are parallel.

Which of the following must be true

Accepted Answer

$$\frac{a}{b}=\frac{c}{d}$$

Answer

$$a=c\ ,\ b=d$$

Answer

$$ab=cd$$

Answer

$$\frac{a}{b}=\frac{d}{c}$$

Answer

$$a+b=c+d$$

Question 10

Two particles have velocity vectors $$ai+bj$$ and $$ai-bj$$ respectively where $$a,\ b>0$$

Which one of the following statement is NOT true

Accepted Answer

the two particles are travelling in opposite directions

Answer

the two particles have the same speed

Answer

the speed of each of the particles is given by $$\sqrt[\ ]{a^2+b^2}$$

Answer

the speed of one particle relative to the other particle is $$2b$$

Answer

the size of the acute angle between the positive x axis and the velocity vector is given by $$ an^{-1}\left(\frac{b}{a} ight)$$

Question 11

$$F$$ is the resultant of the two forces

$$F_1=2i+aj$$ and $$F_2=bi-3j$$

Which of the following is NOT true

Accepted Answer

The magnitude of $$F$$ is equal to the sum of the magnitude of $$F_1$$ and the magnitude of $$F_2$$

Answer

$$F=(2+b)i+(a-3)j$$

Answer

If the system is in equilibrium then $$F=0$$

Answer

If $$F e0$$ , the system will have an acceleration

Answer

If $$a=1$$ , $$b=1$$ and $$mass=1$$ , then the acceleration is $$3i-2j$$

Question 12

Which of the following is NOT correct

Accepted Answer

the SI unit for weight is Kilograms

Answer

the SI unit for time is seconds

Answer

the SI unit for force is Newtons

Answer

the SI unit for displacement is metres

Answer

the SI unit for acceleration is metres per second squared

Question 13

Which of the following most accurately describes $$g$$ , the acceleration due to gravity?

Accepted Answer

$$g$$ varies with distance from the centre of the earth, and on the surface of the earth is approximately equal to $$9.8\ ms^{-2}$$

Answer

$$g$$ is constant and exactly equal to $$9.8\ ms^{-2}$$

Answer

$$g$$ is constant and approximately equal to $$9.8\ ms^{-2}$$

Answer

$$g$$ varies with distance from the centre of the earth, and on the surface of the earth is exactly equal to $$9.8\ ms^{-2}$$

Answer

$$g$$ varies depending on the mass of the falling object but is always approximately equal to $$9.8\ ms^{-2}$$

Question 14

A mass $$\left(m\right)$$ is on a slope. The component of weight acting down the slope

Accepted Answer

is always less than $$mg$$

Answer

is always equal to $$mg$$

Answer

is always greater than $$mg$$

Answer

can be greater than, equal to or less than $$mg$$

Answer

is either less than or equal to $$mg$$

Question 15

A mass is at rest on horizontal ground. The normal reaction force is

Accepted Answer

If no other forces act then it is the same as the weight, but if there is an external force then the normal reaction force may be either less or more than the weight

Answer

Always the same as the weight

Answer

Never the same as the weight

Answer

If no other forces act then it is the same as the weight, but if there is an external force then the normal reaction force will be less than the weight

Answer

If no other forces act then it is the same as the weight, but if there is an external force then the normal reaction force will be more than the weight

Question 16

What is the magnitude of the vector $$12i+5j$$ ?

Accepted Answer

$$13$$

Answer

$$0$$

Answer

$$1$$

Answer

$$5$$

Answer

$$12$$

Question 17

What is the magnitude of the unit vector ?

Accepted Answer

$$1$$

Answer

$$0$$

Answer

$$2$$

Answer

$$\pi$$

Answer

$$i$$

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