Mechanics (Mass, Motion, Force, Acceleration, Momentum, Work, Power, Energy)

1. A simple machine helps a person in doing : [I.A.S. (PRE) 1996]

(a) The same amount of work with slowly.
(b) The same amount of work with lesser force.
(c) Less work.
(d) The same amount of work with much faster.

Correct Answer: (b) The same amount of work with lesser force.

Solution:A simple machine helps a person in doing the same amount of work with lesser force.For example of simple machines are pulley lever wheel screw etc.

2. A man is standing on a sensitive balance. If he inhales deeply the reading of the balance - [U.P.P.S.C.(MAINS)2013]

(a) Increase
(b) Decrease
(c) Remained unaffected
(d) May increase or decrease depending upon the atmospheric pressure.

Correct Answer: (a) Increase

Solution:The reading of the balance is increased if a person inhales the air deeply.Inhaled air will add to the mass of the man and thus his weight goes up slightly.

3. Which of the following is not a vector quantity? [45th B.P.S.C. (Pre) 2001]

(a) Displacement
(b) Force
(c) Velocity
(d) Volume

Correct Answer: (d) Volume

Solution:The vector quantity is defined as the quantity that have both magnitude as well as direction. Displacement, Velocity and Force are the example of vector quantity but volume is a scalar quantity.

4. Which of the following is a vector quantity? [U.P.R.O/A.R.O (MAINS) 2014]

(a) Time
(b) Speed
(c) Displacement
(d) Distance

Correct Answer: (c) Displacement

Solution:The vector quantity is defined as the quantity that have both magnitude as well as direction. Displacement is the example of vector quantity but others are scalar quantity.

5. Which of the following is not a vector quantity? [ 67th B.P.S.C. (Pre) (Re.exam) 2002]

(a) Speed
(b) Torque
(c) Displacement
(d) Velocity

Correct Answer: (a) Speed

Solution:Speed is the scalar quantity while the Torque ,Displacement and Velocity are the example of vector quantity.

6. Which of the following is a scalar quantity? [65th B.P.S.C. (Pre)2019]

(a) Velocity
(b) Pressure
(c) Acceleration
(d) Force

Correct Answer: (b) Pressure

Solution:Force, Acceleration and Velocity are the example of vector quantity while the pressure is scalar quantity.Pressure is defined as the force per unit area.

7. Which of the following is a vector quantity? [I.A.S.(PRE) 1997]

(a) Momentum
(b) Pressure
(c) Energy
(d) Work

Correct Answer: (a) Momentum

Solution:Momentum is a vector quantity while rest of the options are scalar quantity.

8. Which physical quantity is represented by the ratio of momentum and the velocity of the body? [45th B.P.S.C(Pre) 2001]

(a) Velocity
(b) Acceleration
(c) Mass
(d) Force

Correct Answer: (c) Mass

Solution:Momentum is a vector quantity that is product of mass and velocity of an object or particle.
momentum= mass × velocity
so, mass=momentum/velocity.

9. Force is the product of - [45th B.P.S.C.(Pre) 2001]

(a) Mass and velocity
(b) Mass and acceleration
(c) Weight and velocity
(d) Weight and acceleration

Correct Answer: (b) Mass and acceleration

Solution:A force can cause an object with ,mass to change its velocity to accelerate.
Force(F)=Mass × Acceleration=m × a

10. If the number represent volume and surface of cube are equal then , the length of the edge of the cube in terms of the unit of measurement will be - [I.A.S. (PRE) 1997]

(a) 3
(b) 4
(c) 5
(d) 6

Correct Answer: (d) 6

Solution:Volume of cubes=L³ [where L is the length of cube,s edge]
surface area of cubes=6 L²
according to question both are equal to each other
therefore L³ =6 L²
hence L=6