Work Energy and Power-Quiz-5

WORK ENERGY AND POWER Quiz-5

Dear Readers,

Work power energy is the most important chapter when it comes to mechanics, for JEE (Advanced). The chapter is quite tricky and takes a lot of time and devotion on your part to understand and master. But this chapter is a complete gold medal for almost all the questions of the mechanics can be solved by the work power energy approach if you master this topic..

Q1.

•  
  3 m/s
•  
  4 m/s
•  
  5 m/s
•  
  1 m/s

Solution

Q2.

A pump motor is used to deliver water at a certain rate from a given pipe. To obtain n times water from the same pipe in the same time, by what amount should the power of the motor be increased?

•  n^2 times
•  n^3 times
•  n times
•  n^(3/2) times

Solution

Q3.  A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a_c is varying with time t as ac=k^2 rt^2, where k is a constant. The power delivered to the particle by the forces acting on it is

•  Zero
•  mk^2 r^2 t^2
•  mk^2 r^2 t
•  mk^2 rt

Solution

Q4. 

Work done in time t on a body of mass m, which is accelerated from rest to a speed v in time t1 as a function of time t, is given by

•  
  
•  
  
•  
  
•  
  

Solution

Q5.In the above questions, if equal forces are applied on two springs, then

•  More work is done on Q
•  More work is done on P
•  Heir force constants will becomes equal
•  Equal work is done on both the springs

Solution
 

Spring Q has lesser force constant thanP. So Q will develop less restoring force than P. As a result, Q wi8ll suffer more extension. Since force is same in both the cases, more work will be done on Q

Q6. 

In the above question, the maximum power delivered by the agent in pulling up the rope is

•  
  
•  
  
• 
•  
  

Solution

Q7.

•  80 J
•  -80 J
•  -180 J
•  180 J

Solution

Q8.

A car drives along a straight level frictionless road by an engine delivering constant power. Then velocity is directly proportional to

•  t
•  T1/√t
•  √t
•  None of these

Solution

Q9.

An automobile weighing 1200 kg climbs up a hill that rises 1 in 20. Neglecting frictional effects, the minimum power developed by the engine is 9000 W. If g=10 ms^(-2), then the velocity of the automobile is

•  36 kmh^(-1)
•  54 kmh^(-1)
•  72 kmh^(-1)
•  90 kmh^(-1)

Solution

Q10. 

Two small particles of equal masses start moving in opposite directions from a point A in a horizontal circular orbit. Their tangential velocities are v and 2v respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many elastic collisions, other than that at A ,these two particles will again reach The point A?

•  4
•  3
•  2
• 1

Solution