Two cars start moving from the same point on a rectilinear path at the same time, heading to the same destination 90 km away. The first travels at an average speed of 50 km/h and the second at 60 km/h. Deter- mine the time interval separating the arrival of the two cars to their destination.

0.3 hour

Explanation:

From the question given above, the following data were obtained:

Distance travelled = 90 km

Speed of 1st car = 50 km/h

Speed of 2nd car = 60 km/h

Time interval separating the two cars =?

Next, we shall determine the time taken for each car to get to the destination. This can be obtained as follow:

For the 1st car:

Distance travelled (d) = 90 km

Speed of 1st car (S₁) = 50 km/h

Time (t₁) =?

Speed = Distance /time

S₁ = d/t₁

50 = 90 / t₁

Cross multiply

50 × t₁ = 90

Divide both side by 50

t₁ = 90 / 50

t₁ = 1.8 hours

For the 2nd car:

Distance travelled (d) = 90 km

Speed of 2nd car (S₂) = 60 km/h

Time (t₂) =?

Speed = Distance /time

S₂ = d/t₂

60 = 90 / t₂

Cross multiply

60 × t₂ = 90

Divide both side by 60

t₂ = 90 / 60

t₂ = 1.5 hours

Finally, we shall determine the time interval separating the arrival of the two cars. This can be obtained as follow:

Time for the 1st car (t₁) = 1.8 hours

Time for the 2nd (t₂) = 1.5 hours

Time interval separating the two cars (tₛ) =?

tₛ = t₁ – t₂

tₛ = 1.8 – 1.5

tₛ = 0.3 h

Thus, the interval separating the arrival of the two cars is 0.3 hour