Question

11. An electric train is moving with a velocity of 120km/hr. How much distance will it move in

30s?

12. A body is moving with a velocity of 15m/s. If the motion is uniform, what will be the

velocity after 10s?

13. A train travels some distance with a speed of 30km/hr and returns with a speed of

45km/hr Calculate the average speed of the train.

14. A train 100m long moving on a straight level track passes a pole in 5s. Find

(a) the speed of the train

(b) the time it will take to cross a bridge 500m long.

Answer 1

@

(11) Not sure but trying
✒ u = 120km/h = (120×5/18)m/s = 33.3 m/s
✒ t = 30 sec
✒ a = ?
✒ v = ?
in this case acceleration is not given and also final velocity is not given to find acceleration .
So, its not a full question or wrong question .

(12) A body is moving with a uniform velocity of 15 m/s it means velocity is not changing with time , so final velocity after 10 sec = 15m/s

(13) ✒ u = 30km/h
✒ v = 45 km/h
Average speed = (u+v) / 2
✒ ( 30+45) / 2
✒ 75/2
✒ 37.5 m/s

(14) Distance = 100 metre
Time taken = 5 sec
(a) Speed of train = distance / time
✒ 100/5
✒ 20 m/s

(b) Time taken to cover 500 m
✒ (100×5)m = (5×5)sec
✒ 500m = 25 sec

@:-)

Answer 2

Heya,

11. Given,

Velocity of the train = 120 km/hr = 100/3 m/s

Time taken = 30 sec

Distance = Velocity × time

100/3 × 30

= 1000m

= 1km

Distance covered in 30 seconds is 1 km

12 Given,

v = 10 m/s

As the body is moving uniformly there will be no change in velocity.

Velocity after 10 s = 10m/s

13. Let the distance travelled be x

Total distance travelled = 2x

Let t1 = x/30 and t2 = x/45

Average speed = 2x /x/30+x/45)

= 2x / (5x/90)

= 2x/5x/90

=2x/ 5x*90

= 36 km/hr

14. Given,

distance travelled = 100m

Time taken = 5 sec

speed = 100/5

= 20m/s

Time taken = distance/ speed

= 500/20

= 25s

Hope it helps u...........