Speed / velocity related Q ? ?

Question

A car traveling 88 km/hr is 110 m behind a truck traveling 75 km/hr. How long will it take the car to reach the truck?

Answer 1

Let

T = time when the car will reach the truck

The working formula here is

D = VT

where

D = distance travelled

V = velocity

T = time

Let

Dc = distance travelled by the car to catch up with the truck

Dt = distance travelled by truck when car catches up

For the car, the distance travelled when it catches up with the car,

Dc = 110 + Dt = 88(T)

Simplifying,

Dt = 110 - 88T --- call this Equation 1

The second equation is

Dt = 75T and substituting this in Equation 1,

75T = 100 - 88T

Combining terms,

75T + 88T = 100

163T = 100

T = 0.61 hr

T = 37 minutes

Answer 2

How long = .100km/[(88 - 75)km/hr]

Answer 3

88 km/hrX1000m/1kmX1 hr/3600 sec= 24.4 m/s

75 km/hr X 1000m/1kmX1hr/3600 sec=20.8 m/s

distance=velocityX time

distance of truck 1  = distance of truck 2+110m

24.4t=20.8t+110

3.57t=110

t= 30.8 seconds

Note; Pointy made a mistake of calculating kilometers/hr and threw in distance that was in meters and not kilometers. This is why he is off in his calculations.

Mark below would of been right but he saw 100 meters and assumed it was 100 kilometers. Follow the units your self, you will see they messed up the unit consistency.