Question

a) A train 40m long passes over a bridge 200m long at a speed of 36km/hr. How long will it take to pass completely over the bridge

b). A boy start running from his house with a uniform speed and takes 1hour to reach the playground is 3.6km. calculate the speed in km/hr,m/s,and cm/s

C) which of the following is moving faster justify the answer
1)a scooter moving with a speed 300m/min
2) a car moving with a speed of 36km/he.

Answer 1

A)
Total length to be covered = 200+40 = 240

speed = 36km/hr = 10m/s

therefore time taken =total length/speed
= 240/10 = 24seconds

B)
time ,t=1hour=60mins=3600 secs
distance travelled, s=3.6 km=3600 m =36000 cm

Speed = displacement/ time
=3.6/1=3.6km/hr
=3600/3600=1 m/sec
=36000/3600=10 cm/sec

c)
1 hour = 60 mins
1 km= 1000 m

thus we can write,
36 km/hr= (36*1000)/60=600 m/min

now ,
speed ofscooter=300m/min
speed of car=36km/hr=600m/min

since 600>300

Car is moving faster