Practice Mechanics work and energy - general science mcq Online Quiz (set-1) For All Competitive Exams
Q-1) The maximum kinetic energy of a planet moving around the sun is at a position
(a)
(b)
(c)
(d)
Q-2) The number of significant figures in 0.00060 m is
(a)
(b)
(c)
(d)
According to rules of significant figures.
Q-3) If the number representing volume and surface area of a cube are equal, then the length of the edge of the cube in terms of the unit of measurement will be
(a)
(b)
(c)
(d)
Q-4) Time period of a simple pendulum inside a satellite orbiting earth is
(a)
(b)
(c)
(d)
Since, T = $2π√{l/g}$
but inside the satellite g = 0
So, T = ∞
Q-5) Two identical particles move towards each other with velocity 2v and v respectively. The velocity of centre of mass is
(a)
(b)
(c)
(d)
Q-6) A truck, a car and a motorcycle have equal kinetic energies. If equal, stopping forces are applied and they stop after travelling a distance of X, Y and Z respectively, then
(a)
(b)
(c)
(d)
Q-7) Consider the following statements :
- A person standing for a long time with a suitcase on his head does no work in terms of physics.
- There cannot be any displacement of an object in the absence of any force acting on it.
- The law of conservation of energy is valid in all situations and for all kinds of transformations.
Which of these statements is/are correct ?
(a)
(b)
(c)
(d)
Yes. If a particle is moving and there is no force on it, then it will continue to move with constant velocity.
Thus it will have displacement.
Q-8) Consider the following statements.
A 4-wheel vehicle moving in a sharp circular path at high speed will
- Overturn about its outer wheels
- Overturn about its inner wheels
- Skid outwards
- Skid inwards
Which of these statements are correct?
(a)
(b)
(c)
(d)
Q-9) A body weighs less at the equator than at the poles because:
- earth rotates about its axis.
- the ice cap at the poles increases gravitational pull.
- equatorial diameter is greater than the polar diameter.
- of some unknown facts.
Which of the statements given above is/are incorrect?
(a)
(b)
(c)
(d)
For a given point on the surface of the earth, g decreases as w increases.
Hence, the body weighs less at the equator than at the poles also equatorial diameter is greater than the polar diameter.
So according to g = ${GM}/{R^2}$ value of g decreases.
Q-10) Consider the following statements :
- Copernicus discovered that the earth moves around the sun.
- An astronaut cannot use a straw to sip a drink on the surface of the moon.
- The S.I. unit of weight is kilogram.
Which of these statements is/are correct?
(a)
(b)
(c)
(d)
The weight of an object is the force on the object due to gravity.
The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton.
Q-11) The centre of mass of triangle shown in figure has coordinates
(a)
(b)
(c)
(d)
We can assume that three particles of equal mass m are placed at the corners of triangle${r_1}↖{→} = Oi↖{˄} + Oj↖{˄},{r_2}↖{→} = bi↖{˄} + Oj↖{˄} and {r_3}↖{→} = Oi↖{˄} + hj↖{˄}$∴ $r_{cm}↖{→}={m_1{r_1}↖{→}+m_2{r_2}↖{→}+m_3{r_3}↖{→}}/{m_1+m_2+m_3}=b/3{i}↖{˄}+h/3{j}↖{˄}$i.e. coordinates of centre of mass is $(b/3, h/3)$
Q-12) A man is standing on a sensitive balance. If he inhales deeply, the reading of the balance
(a)
(b)
(c)
(d)
Q-13) Swimming is possible on account of
(a)
(b)
(c)
(d)
When the swimmer push some water in backward direction, then he get some momentum in forward direction from water & starts to swim. This is according to Newton’s third law. (action-reaction force).
Q-14) Force is the product of
(a)
(b)
(c)
(d)
Q-15) When a moving bus suddenly applies brakes, the passengers sitting in it fall in the forward direction. This can be explained by
(a)
(b)
(c)
(d)
Q-16) The circular motion of a particle with constant speed is
(a)
(b)
(c)
(d)
In the circular motion of a particle with constant speed, the particle repeats its motion after a regular interval of time but does not oscillate about a fixed point.
So, the motion of particles is periodic but not simple harmonic.
Q-17) A simple machine helps a person in doing
(a)
(b)
(c)
(d)
Q-18) A simple machine helps a person in doing:
(a)
(b)
(c)
(d)
Q-19) Consider the following two statements:
- Linear momentum of a system of particles is zero.
- Kinetic energy of a system of particles is zero.
Then
(a)
(b)
(c)
(d)
If $L↖{→}$ = 0 ⇒ K. E may or may not be zero.
If K.E = 0, $L↖{→}$ = 0
Q-20) A coin is placed on a rotating disc and is stationary w.r.t. the disc, then the direction of friction is
(a)
(b)
(c)
(d)
Friction provides centripetal force to the coin, hence acts towards the centre of the disc.