A space craft flying in a straight course with a velocity of 75 k m s fires its rocket motors for 6 . 0 s . At the end of this time, its speed is 120 k m s in the same direction. Find the space craft's average acceleration while the motors were firing.

Given: u = 75 k m s ; v = 120 k m s ; t = 6 s Acceleration = ( f i n a l v e l o c i t y - i n i t i a l v e l o c i t y ) t i m e t a k e n = ( 120 - 75 ) 6 = 7 . 5 m s 2

A space craft flying in a straight course with a velocity of 75 k m s fires its rocket motors for 6 . 0 s . At the end of this time, its speed is 120 k m s in the same direction. Find the space craft's average acceleration while the motors were firing.

Given: u = 75 k m s ; v = 120 k m s ; t = 6 s Acceleration = ( f i n a l v e l o c i t y - i n i t i a l v e l o c i t y ) t i m e t a k e n = ( 120 - 75 ) 6 = 7 . 5 m s 2

A space craft flying in a straight course with a velocity of 75 k m s fires its rocket motors for 6 . 0 s . At the end of this time, its speed is 120 k m s in the same direction. Find the distance travelled by the space craft in the first 10 s after the rocket motors were started, the motors having been in action for only 6 . 0 s .

Given: u = 75 k m s ; v = 120 k m s ; Acceleration = ( f i n a l v e l o c i t y - i n i t i a l v e l o c i t y ) t i m e t a k e n = ( 120 - 75 ) 6 = 7 . 5 m s 2 Distance travelled by the space craft in t = 10 s = Distance travelled in first 6 s + distance travelled in next 4 s Distance travelled in first 6 s : s 1 = u t + 1 2 a t 2 s 1 = ( 75 ) ( 6 ) + 1 2 ( 7 . 5 ) ( 6 ) 2 = 450 + 135 = 585 k m At the end of 6 s , the speed is 120 k m s Distance covered in the next 4 s : s 2 = speed × time = 120 × 4 = 480 k m ∴ the distance covered by the aircraft in 10 s = s 1 + s 2 = 585 k m + 480 k m = 1065 k m