Question

A racehorse is running with a uniform speed of 69 km/hr along a straightaway. What is the time it takes for the horse to cover 400 meters?

21 seconds

2.1 minutes

0.35 hours

27.6 hours

Answer 1

The answer to your question is: 21 seconds

Step-by-step explanation:

Data

speed = v = 69 km/h

distance = d = 400 m

time = t = ?

Formula

v = d / t

t = d / v

Process

Convert 400 m to km

1 km ----------------- 1000 m

x ------------------- 400 m

x = (400 x 1) / 1000

x = 0.4 km

Substitution

t = 0.4 / 69

t = 0.006 h

Covert time to minutes and seconds

60 min -------------------- 1 h

x ------------------- 0.006 h

x = (0.006 x 60) / 1

x = 0.36 min

Convert time to seconds

1 min ------------------ 60 s

0.36 min -------------- x

x = (0.36 x 60) / 1

x = 21.6 seconds ≈ 21 seconds

Answer 2

21 seconds

Step-by-step explanation:

First, convert km/hr to m/s.

69 km/hr × (1000 m / km) × (1 hr / 3600 s) = 19.2 m/s

Distance = rate × time

400 m = 19.2 m/s × t

t = 20.9 s

Rounded to two significant figures, it takes the horse 21 seconds.