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Engineering
121 Views   |

When a body falls freely towards the earth, then its total energy

• Option 1)

increases

• Option 2)

decreases

• Option 3)

remains constant

• Option 4)

first increases and then decreases

As we discussed in concept If only conservative forces act on a system, total mechnical energy remains constant - -   Remains constant Option 1) increases Option is incorrect Option 2) decreases Option is incorrect Option 3) remains constant   Option is correct Option 4) first increases and then decreases   Option is incorrect
Engineering
254 Views   |

When a ball is thrown up vertically with velocity vo it reaches a maximum height of h. If one wishes to triple the maximum height then the ball should be thrown with velocity.

• Option 1)

vo√3

• Option 2)

3vo

• Option 3)

9vo

• Option 4)

(3/2)vo

As we discussed in concept Potential Energy - - wherein    At Maximum height V=0 At  h1=3h Option 1) vo√3    Option is correct Option 2) 3vo  Option is incorrect Option 3) 9vo  Option is incorrect Option 4) (3/2)vo Option is incorrect
Engineering
170 Views   |

Two bodies of masses 0.1kg and 0.4kg move towards each other with velocities 1 m/s and 0.1m/s respectively. After collision they stick together. In 10sec the combined mass travels?

• Option 1)

120 m

• Option 2)

0.12 m

• Option 3)

12 m

• Option 4)

1.2 m

As we learned in concept Definition of work by constant force - - wherein The product of  magnitude of force  magnitude of displacement  and cosine of the angle between them      Distance travelled by combined mass  Option 1) 120 m  Option is incorrect Option 2) 0.12 m Option is incorrect Option 3) 12 m  Option is incorrect Option 4) 1.2 m Option is correct
Engineering
88 Views   |

The work done on an object does not depend upon the

• Option 1)

displacement

• Option 2)

force applied

• Option 3)

angle between force and displacement

• Option 4)

initial velocity of the object

As we  learned in concept Negative Work - - wherein is the angle between force vector and displacement vector    angle between force and displacement Option 1) displacement Option is incorrect Option 2) force applied   Option is incorrect Option 3) angle between force and displacement      Option is correct Option 4) initial velocity of the object   Option is incorrect
Engineering
448 Views   |

The graph between the resistive force F acting on a body and the distance covered by the body is shown is shown in the figure. The mass of the body is 60 kg and the initial velocity is 3m/s. When the distance covered by the body is 4m, its kinetic energy will be

• Option 1)

250 J

• Option 2)

230 J

• Option 3)

200 J

• Option 4)

220 J

As we learnt in  Kinetic energy - - wherein kinetic Energy is never negative     Work done against resistance force = Area between F-x graph       Final K.E. = 270 - 40 = 230 J Option 1) 250 J Incorrect Option 2) 230 J Correct Option 3) 200 J Incorrect Option 4) 220 J Incorrect
Engineering
163 Views   |

In case of negative work, the angle between the force and displacement is

• Option 1)

$0^{0}$

• Option 2)

$45^{0}$

• Option 3)

$90^{0}$

• Option 4)

$180^{0}$

As we discussed in concept Negative Work - - wherein is the angle between force vector and displacement vector     Option 1) Option is incorrect Option 2) Option is incorrect Option 3) Option is incorrect Option 4) Option is correct
Engineering
98 Views   |

How are Joule (J) and ergs (erg) related?

• Option 1)

$1J= 10^{7} erg$

• Option 2)

$1 erg=10^{-7} J$

• Option 3)

$1J= 10^{-7} erg$

• Option 4)

None of these

As we discussed in concept Definition of work by constant force - w = - wherein The scalar product of the force vector () and the displacement vector ()     Option 1)   Option is incorrect Option 2) Option is correct Option 3) Option is incorrect Option 4) None of these Option is incorrect
Engineering
606 Views   |

A metal ball of mass 2 kg moving with speed of 36km/h is having a collision with a stationary ball of mass 3kg. If after collision, both the balls move together, the loss in kinetic energy due to collision is

• Option 1)

80 J

• Option 2)

40 J

• Option 3)

60 J

• Option 4)

160 J

As we discussed in concept If only conservative forces act on a system, total mechnical energy remains constant - -     on putting the value we get 60J Option 1) 80 J  Option is incorrect Option 2) 40 J  Option is incorrect Option 3) 60 J  Option is correct Option 4) 160 J Option is incorrect
Engineering
96 Views   |

A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be

$(g=10\, \, ms^{-2})$

• Option 1)

6 ×103 J

• Option 2)

6 J

• Option 3)

0.6 J

• Option 4)

zero

As we discussed in concept Zero Work - - wherein Force and  displacement vectors are Perpendicular to each other     Option 1) 6 ×103 J Option is incorrect Option 2) 6 J Option is incorrect Option 3) 0.6 J Option is incorrect Option 4) zero Option is correct
Engineering
548 Views   |

A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car

• Option 1)

does not change

• Option 2)

becomes twice to that of initial

• Option 3)

becomes 4 times that of initial

• Option 4)

becomes 16 times that of initial

As we discussed in concept Potential Energy - - wherein    Remains Same (No Change) because potential energy is independent of velocity. Option 1) does not change Option is correct Option 2) becomes twice to that of initial   Option is incorrect Option 3) becomes 4 times that of initial   Option is incorrect Option 4) becomes 16 times that of initial   Option is incorrect
Engineering
86 Views   |

A bullet is fired from a riffle. If the riffle recoils freely, then the kinetic energy of the rifle will be?

• Option 1)

same as that of bullet

• Option 2)

more than that of bullet

• Option 3)

less than that of bullet

• Option 4)

none of these

As we discussed in concept Kinetic energy - - wherein kinetic Energy is never negative     less than that of bullet  Option 1) same as that of bullet  Option is incorrect Option 2) more than that of bullet  Option is incorrect Option 3) less than that of bullet  Option is correct Option 4) none of these Option is incorrect
Engineering
602 Views   |

A vertical spring with force constant 'k' is fixed on a table. A ball of mass 'm' at height 'h' above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance d. The net work done in the process is.

• Option 1)

mg(h + d) - (1/2)kd2

• Option 2)

mg(h - d) - (1/2)kd2

• Option 3)

mg(h - d) + (1/2)kd2

• Option 4)

mg(h + d) (1/2)kd2

As we discussed in concept If only conservative forces act on a system, total mechnical energy remains constant - -     Option 1) mg(h + d) - (1/2)kd2    Option is correct Option 2) mg(h - d) - (1/2)kd2  Option is incorrect Option 3) mg(h - d) + (1/2)kd2    Option is incorrect Option 4) mg(h + d) (1/2)kd2   Option is incorrect
Engineering
163 Views   |

A body is falling from a height h. After it has fallen a height h/2 , it will possess

• Option 1)

only potential energy

• Option 2)

only kinetic energy

• Option 3)

half potential and half kinetic energy

• Option 4)

more kinetic and less potential energy

Option 3

Engineering
326 Views   |

A block of mass 10kg is moving in x-direction with a constant speed of 10 m/s . It is subjected to a retarding force F=-0.1 x joule / meter during its travel from x=20 meter to x=30 meter. Its final kinetic energy will be.

• Option 1)

475 J

• Option 2)

450 J

• Option 3)

275 J

• Option 4)

250 J

As we discussed in Concept Net work done by all the forces give the change in kinetic energy - - wherein         Option 1) 475 J  Option is correct Option 2) 450 J  Option is incorrect Option 3) 275 J Option is incorrect Option 4) 250 J Option is incorrect
Engineering
373 Views   |

A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg, which is moving in the same direction with a velocity of 4m/s. If the collision is elastic their velocities after collision will be respectively?

• Option 1)

12m/s, 6m/s

• Option 2)

8 m/s, 10 m/s

• Option 3)

6m/s, 12m/s

• Option 4)

10m/s, 8m/s

As we discussed in concept Net work done by all the forces give the change in kinetic energy - - wherein       on putting the values Option 1) 12m/s, 6m/s  Option is incorrect Option 2) 8 m/s, 10 m/s  Option is incorrect Option 3) 6m/s, 12m/s  Option is correct Option 4) 10m/s, 8m/s Option is incorrect
Engineering
118 Views   |

A 12 HP motor has to be operated 8 hours/day. How much will it cost at the rate of 25 paisa/kWh in 20 days

• Option 1)

Rs. 350

• Option 2)

Rs. 358

• Option 3)

Rs. 375

• Option 4)

Rs. 397

As we discussed in concept Kinetic energy - - wherein kinetic Energy is frame dependent   E= Power time in hours/1000 It is used for 10 days Energy Consumed    Option 1) Rs. 350 Option is incorrect Option 2) Rs. 358 Option is correct Option 3) Rs. 375 Option is incorrect Option 4) Rs. 397 Option is incorrect
Engineering
272 Views   |

For inelastic collision between two spherical rigid bodies

• Option 1)

the total kinetic energy is conserved

• Option 2)

the total potential energy is conserved

• Option 3)

the linear momentum is not conserved

• Option 4)

the linear momentum is conserved

As we learnt in  Kinetic energy - - wherein kinetic Energy is frame dependent   The linear momentum is conserved. Option 1) the total kinetic energy is conserved    Option is incorrect Option 2) the total potential energy is conserved      Option is incorrect Option 3) the linear momentum is not conserved    Option is incorrect Option 4) the linear momentum is conserved Option is correct
Engineering
90 Views   |

An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same

• Option 1)

acceleration

• Option 2)

momenta

• Option 3)

potential energy

• Option 4)

kinetic energy

As we learnt in  Definition of work by constant force - - wherein The product of  magnitude of force  magnitude of displacement  and cosine of the angle between them    Acceleration due to gravity is independent of Mass of the body. Option 1) acceleration Option is correct Option 2) momenta Option is incorrect Option 3) potential energy Option is incorrect Option 4) kinetic energy Option is...
Engineering
599 Views   |

A weight lifter lifts 300 kg from the ground to a height of 4m in 3 seconds. The average power generated by him is

• Option 1)

5880 W

• Option 2)

3920 W

• Option 3)

1960 W

• Option 4)

4410 W

As we learnt in  Work done by time dependent force - - wherein Where and are force and velocity vector at any instant     Option 1) 5880 W Option is incorrect Option 2) 3920 W Option is incorrect Option 3) 1960 W Option is correct Option 4) 4410 W Option is incorrect
Engineering
663 Views   |

A shell of mass 'm' moving with velocity v suddenly break into two pieces the part having mass m/3 remains stationary. The velocity of other part will be?

• Option 1)

(2/3) v

• Option 2)

(7/5) v

• Option 3)

(3/2)v

• Option 4)

none of these

As we learnt in  Kinetic energy - - wherein kinetic Energy is frame dependent    Mass of two piece are      Option 1) (2/3) v  Option is incorrect Option 2) (7/5) v  Option is incorrect Option 3)  (3/2)v  Option is correct Option 4) none of these   Option is incorrect
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