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Engineering
335 Views   |  

Two objects of equal mass hit a wall with the same velocity. They both rebound with the same velocity. Both objects experience the same momentum change but one experiences twice the force as the other. Which of the following statements is true?

  • Option 1)

    the contact time between the object and the wall of one is twice the contact time of the other

  • Option 2)

    the contact time between the object and the wall of one is equal to the contact time of the other

  • Option 3)

    the contact time between the object and the wall of one is one-half the contact time of the other

  • Option 4)

    the change in the kinetic energy is the same for the two objects.

 
As we learnt in Perfectly Elastic Collision - - wherein   The contact time between the object and the wall of one is twice the contact time of other.    Option 1) the contact time between the object and the wall of one is twice the contact time of the other Correct Option 2) the contact time between the object and the wall of one is equal to the contact time of the other Incorrect Option...
Engineering
459 Views   |  

Two objects collide and stick together. Which of the following is false?
 

  • Option 1)

    momentum is conserved
     

  • Option 2)

     kinetic energy is lost
     

  • Option 3)

    kinetic energy is conserved
        

  • Option 4)

    momentum is lost
     

 
As we discussed in Perfectly Inelastic Collision - - wherein    Momentum remains conserved but kinetic energy does not. Option 1) momentum is conserved   Incorrect Option 2)  kinetic energy is lost   Incorrect Option 3) kinetic energy is conserved      Correct Option 4) momentum is lost   Incorrect
Engineering
102 Views   |  

The Center of Mass of which of the following objects would not lie within the body itself?

  • Option 1)

    Cricket Ball    

  • Option 2)

    Stone

  • Option 3)

    Frisbee

  • Option 4)

    Paperback book

 
As we discussed in Centre of Mass - The cenre of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero or the point where if a force is applied it moves in the direction of the force without rotating. -    Frisbee Option 1) Cricket Ball     Incorrect Option 2) Stone Incorrect Option 3) Frisbee Correct Option...
Engineering
120 Views   |  

If each mass in the figure is 1 kg, what is the x location of the center of mass?

  • Option 1)

    0.50  

  • Option 2)

    0.67

  • Option 3)

    1.00

  • Option 4)

    1.33

 
As we discussed in Centre of Mass of a system of N discrete particles - - wherein m1, m2 ........... are mass of each  particle  x1, x2 ..........y1, y2 ............ z1, z2 are respectively x, y, & z coordinates of particles.     Option 1) 0.50   Incorrect Option 2) 0.67 Incorrect Option 3) 1.00 Correct Option 4) 1.33 Incorrect
Engineering
215 Views   |  

An open box-car has a mass of 30,000 kg and is moving on a level railroad track at 4.00 m/s. 1,000 kg of water falls straight down into the box-car. The velocity of the box-car after the water falls into the box-car is

  • Option 1)

    7.01 m/s.

  • Option 2)

    6.55 m/s.

  • Option 3)

    5.02 m/s.

  • Option 4)

    3.87 m/s.

 
As we discussed in Perfectly Inelastic Collision - - wherein Two bodies stick together after the collision ,so there will be a final common velocity (v)     Option 1) 7.01 m/s. Incorrect Option 2) 6.55 m/s. Incorrect Option 3) 5.02 m/s. Incorrect Option 4) 3.87 m/s. Correct
Engineering
345 Views   |  

An astronaut in a space suit is motionless in outer space. The propulsion unit strapped to her back ejects some gas with a velocity of 50 m/s. The astronaut recoils with a velocity of 1.0 m/s. If the mass of the astronaut and space suit after the gas is ejected is 120 kg, the mass of the gas ejected is

  • Option 1)

    1.0 kg.

  • Option 2)

    1.9 kg.

  • Option 3)

    2.4 kg.

  • Option 4)

    3.00 kg.

 
As we dicussed in Elastic Collision in 2 dimension - - wherein    Velocity of the gas is  Mass of astronaut = 120 kg MV=mv   Option 1) 1.0 kg. Incorrect Option 2) 1.9 kg. Incorrect Option 3) 2.4 kg. Correct Option 4) 3.00 kg. Incorrect
Engineering
496 Views   |  

A rocket with a mass of 500 grams is launched straight up. It achieves a velocity of 20.0 m/s in 2.00 seconds. The average thrust force of the engines on the rocket is

  • Option 1)

    7.50 N.

  • Option 2)

    9.90 N.

  • Option 3)

    12.0 N.

  • Option 4)

    13.5 N.

 
As we learnt Power if the force is constant - - wherein              Option 1) 7.50 N. This option is incorrect Option 2) 9.90 N. This option is correct Option 3) 12.0 N. This option is incorrect Option 4) 13.5 N. This option is incorrect
Engineering
266 Views   |  

A rifle fires a bullet. Immediately after the bullet is fired, which of the following is NOT true?

  • Option 1)

    the rifle and the bullet have the same magnitude of momentum
     

  • Option 2)

    the force on the rifle due to the bullet and the force on the bullet due to the rifle have the same magnitude
     

  • Option 3)

    the rifle and the bullet do not have the same kinetic energy
     

  • Option 4)

    the rifle and the bullet have the same kinetic energy
     

 
  Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein    the rifle and the sullet have the same Kinetic energy    Option 1) the rifle and the bullet have the same magnitude of momentum   This option is incorrect Option 2) the force on the rifle due to the bullet and the force on the bullet due to the rifle have the same...
Engineering
384 Views   |  

A 90 kg person is sitting in a boat at rest with a mass of 100 kg. In the boat is a stone with a mass of 5.0 kg. The person throws the stone at 4.00 m/s horizontally in the NORTH direction. The velocity of the person and the boat after the throwing the stone is
 

  • Option 1)

    2.00 m/s NORTH

  • Option 2)

    1.21 m/s SOUTH.

  • Option 3)

    1.21 m/s NORTH.

  • Option 4)

    0.11 m/s SOUTH.

 
As we learnt in Perfectly Inelastic Collision - - wherein Two bodies stick together after the collision ,so there will be a final common velocity (v)     where 20 kg is Momentum     Option 1) 2.00 m/s NORTH This option is incorrect Option 2) 1.21 m/s SOUTH. This option is incorrect Option 3) 1.21 m/s NORTH. This option is incorrect Option 4) 0.11 m/s SOUTH. This option is correct
Engineering
355 Views   |  

A 4.00 kg ball is traveling at 5.00 m/s and strikes a wall. The 4.00 kg ball bounces off the wall with a velocity of 4.0 m/s. The change in momentum of the ball is
 

  • Option 1)

    8.0 kg m/s.

  • Option 2)

    13 kg m/s.

  • Option 3)

    26 kg m/s

  • Option 4)

    36 kg m/s.

 
  Coffecient of Restitution (e) - - wherein Ratio of relative velocity after collision to relative velocity before collision.       Option 1) 8.0 kg m/s. This option is incorrect Option 2) 13 kg m/s. This option is incorrect Option 3) 26 kg m/s This option is incorrect Option 4) 36 kg m/s. This option is correct
Engineering
95 Views   |  

A 4.00 kg ball is moving at 2.00 m/s to the WEST and a 6.00 kg ball is moving at 2.00 m/s to the NORTH. The total momentum of the system is
 

  • Option 1)

    21.6 kg m/s at an angle of 17.7 degrees NORTH of WEST.
     

  • Option 2)

    14.4 kg m/s at an angle of 45.2 degrees SOUTH of WEST.
     

  • Option 3)

    21.6 kg m/s at an angle of 45.2 degrees SOUTH of WEST.
     

  • Option 4)

    14.4 kg m/s at an angle of 56.3 degrees NORTH of WEST.
     

 
As discussed in Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein     Magnitude of                                                                         of  west Option 1) 21.6 kg m/s at an angle of 17.7 degrees NORTH of WEST.   This solution is incorrect. Option 2) 14.4 kg m/s at an angle of 45.2 degrees SOUTH of...
Engineering
134 Views   |  

A 30.0 kg mass falls from a height of 4.0 m. The momentum of the mass just before it hits the ground  is

  • Option 1)

    144.2 kg m/s

  • Option 2)

    187.8 kg m/s.

  • Option 3)

    320.0 kg m/s.

  • Option 4)

    442.4 kg m/s.

 
As discussed in Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein              Option 1) 144.2 kg m/s This solution is incorrect Option 2) 187.8 kg m/s. This solution is incorrect Option 3) 320.0 kg m/s. This solution is incorrect Option 4) 442.4 kg m/s. This solution is incorrect
Engineering
153 Views   |  

A 3.000 kg ball is pitched with a kinetic energy of 20.00 Joules. Then the momentum of the ball is

  • Option 1)

    7.500 kg m/s.
     

  • Option 2)

    8.350 kg m/s.

  • Option 3)

    9.450 kg m/s.

  • Option 4)

    10.95 kg m/s.

 
As discussed in Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein     Option 1) 7.500 kg m/s.   This solution is incorrect. Option 2) 8.350 kg m/s. This solution is incorrect. Option 3) 9.450 kg m/s. This solution is incorrect. Option 4) 10.95 kg m/s. This solution is correct.
Engineering
287 Views   |  

A 3.0 kg object is moving to the right at 4.0 m/s. It collides in a perfectly inelastic collision with a 6.0 kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision?

  • Option 1)

    62 J

  • Option 2)

    25 J

  • Option 3)

    12 J

  • Option 4)

    0.0 J

 
As we discussed in concept Perfectly Inelastic Collision - - wherein Two bodies stick together after the collision ,so there will be a final common velocity (v)         Option 1) 62 J This option is incorrect. Option 2) 25 J This option is incorrect. Option 3) 12 J This option is incorrect. Option 4) 0.0 J This option is incorrect.
Engineering
360 Views   |  

A 140 gm baseball with a velocity of 25.0 m/s is hit by a baseball bat and leaves at 30.0 m/s in the opposite direction. If the ball was in contact with the bat for 12.0 ms, what is the average force on the ball?
 

  • Option 1)

    750 N

  • Option 2)

    642 N

  • Option 3)

    550 N

  • Option 4)

    482 N

 
As we discussed in concept Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein     Option 1) 750 N This option is incorrect. Option 2) 642 N This option is correct. Option 3) 550 N This option is incorrect. Option 4) 482 N This option is incorrect.
Engineering
257 Views   |  

A 1200 kg car travels at 25.0 m/s and collides head-on in a perfectly inelastic collision with a stationary 2400 kg truck. The kinetic energy lost in the collision is

  • Option 1)

    330,000 J

  • Option 2)

    250,000 J.

  • Option 3)

    125,000 J.

  • Option 4)

    95,000 J.

 
As we discussed in concept Perfectly Inelastic Collision - - wherein Two bodies stick together after the collision ,so there will be a final common velocity (v)    From conservation of Linear Momentum After calculating, we get lost in kinetic energy as 250,000 J Option 1) 330,000 J This option is incorrect. Option 2) 250,000 J. This option is correct. Option 3) 125,000 J. This option...
Engineering
453 Views   |  

A 1200 kg car is moving at 5.0 m/s EAST. It strikes an 1800 kg car at rest. The cars have an elastic collision and move in the EAST or WEST direction. The velocity of the 1800 kg car after the collision is
 

  • Option 1)

    3.0 m/s WEST

  • Option 2)

    1.0 m/s EAST    

  • Option 3)

    4.0 m/s EAST

  • Option 4)

    4.0 m/s WEST

 
As we learnt in  Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein    Collison is perfectly elastic i.e., Momentum remains conserved   Option 1) 3.0 m/s WEST Correct Option 2) 1.0 m/s EAST     Incorrect Option 3) 4.0 m/s EAST Incorrect Option 4) 4.0 m/s WEST Incorrect
Engineering
171 Views   |  

A 100 kg mass is blown apart into a 90.0 kg piece and a 10.0 kg piece. After the blast, the two masses are moving apart with a relative velocity of 100 m/s. The velocity of the 10.0 kg mass after the explosion is 90.0 m/s. The total kinetic energy of the two masses after the explosion is

  • Option 1)

    63,200 J.

  • Option 2)

    45,000 J.

  • Option 3)

    30,400 J.

  • Option 4)

    23,400 J.

 

take it the reverse way.. like two mases colliding to form one mass and after collision the complete mass is at rest. so

m1v1+m2v2/m1+m2=0

solve for v2 and substitue it in the next equation u will get the answer

 

Engineering
361 Views   |  

A 3.000 kg ball is pitched with a kinetic energy of 20.00 Joules. Then the momentum of the ball is

  • Option 1)

    5.48 kg m/s     

  • Option 2)

    8.35 kg m/s     

  • Option 3)

    10.95 kg m/s     

  • Option 4)

    9.45 kg m/s     

 
As learnt in Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein     Option 1) 5.48 kg m/s      This option is incorrect Option 2) 8.35 kg m/s      This option is incorrect Option 3) 10.95 kg m/s      This option is correct Option 4) 9.45 kg m/s      This option is incorrect
Engineering
77 Views   |  

 If the momentum of a ball is doubled, then the kinetic energy is
 

  • Option 1)

    0.5 times larger.
     

  • Option 2)

    2 times larger.
     

  • Option 3)

    3 times larger.
     

  • Option 4)

    4 times larger.
     

 
As learnt in Perfectly Elastic Collision - Law of conservation of momentum and that of Kinetic Energy hold good. - wherein  If the momentum of a ball is doubled, then the kinetic energy is four times larger. Option 1) 0.5 times larger.     This option is incorrect Option 2) 2 times larger.   This option is incorrect Option 3) 3 times larger.   This option is incorrect Option 4) 4...
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