Please solve both the questions

68.  A body thrown vertically upwards reaches a maximum height of 4 m. It then returns to the ground.  The distance travelled by the body is ____________ m

69.  If a 100 m long train is travelling with a speed of 100 m/s, find the time taken (in sec) by it to cross a 400 m long bridge
 

 

Dear Student 

69. Total distance covered by train to cross the bridge = Length of bridge + length of train 
     so total distance = 400+100 = 500m
     speed = 100 m/s
     so time =$\frac{dis\tan ce}{speed}= \frac{500}{100}= 5 sec$
68. Total distance = (distance travelled in reaching max height ) x 2       as distance going up and coming down are same
                             = 4x2 = 8 m

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