Correct option is



A body covers one-third of the distance with a velocity v1, the second one-third of the distance with a velocity v2 and the remaining distance with a velocity v3. The average velocity is


Between the two station, a train accelerates from res uniformly at first, then moves with constant velocity and finally retards uniforms to come to rest. If the ratio of the time taken be 1 : 8 : 1 and the maximum speed attained be 60 km/h, then what is the average speed over the whole journey ?


A particle moving in a straight line covers half the distance with speed of 3 m/s. The other half of the distance is covered in two equal time intervals with speeds of 4.5 m/s and 7.5 m/s, respectively. The average speed of the particle during this motion is


Taxies leave the station X  for Y every 10 min. Simultaneously, a taxi also leaves the station Y for station X every 10 min. The taxies move at the same constant speed and go from X and Y or vice-versa in 2h. How many taxies coming from the other side will meet each taxi enroute from Y and X?



The relation between time t and distance x is  where  are constant. The retardation is


The displacement x of a particle moving in one dimension under the action of a constant force is related to time t by the equation , where x is in m and t is in s. Find the displacement of the particle when us velocity is zero


The velocity of light emitted by a source S, observed by an observe O, who is at rest with respect to S, is c. If the observe moves away from S with velocity v, the velocity of light as observed will


A drunkard is waking along a straight road. He takes 5 steps forward and 3 steps backward and so on. each step is 1 m long and takes 1s. There is a pit on the road 11 m away from the starting point. The drunkard will fall into the pit after


A person moves 30 m north and then 30 m towards east and finally 30  m in south-west direction. The displacement of the person from the origin will be


The deceleration experienced by a moving motor boat, after its engine is cut-off is given by dv/dt = – k v3, where k is constant. If v0 is the magnitude of the velocity at cut-off, the magnitude of the velocity at a time t after the cut-off is