# How to Work out the Horsepower to Accelerate a Car of Known Mass

What is the horsepower required to accelerate a 400 Ib car from rest to 60 mph in 10 seconds

(a) What is the kg equivalance of 4000 Ib?

(b) What is the m/s equivalance of 60 mph?

(c) What is the acceleration in m/s2?

(d) What is the final kinetic energy?

(e) What is the average power in Watts?

(f) What is the average power in HP?

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#### Solution Preview

(a) As we convert 1 Ib to kg as 1 Ib = 0.4536 kg (2 dec pl)

4000 lb = 4000 x conversion factor (Ib - kg) = 4000 x 0.4536 kg

4000 Ib = 1814.4 kg

(b) 1 mph = 1.6093 km/h (4 dec pl) [1]

1 mph = 1.6093 x 1000 m/h = 1609.3 m/h

As one hour equals 3600 seconds we convert 1 mph to m/s equivalent

1 mph = 1609.3/3600 m/s

Thus

60 mph ...

#### Solution Summary

The solution explains how to determine the horsepower required to accelerate a 400 Ib car from rest to 60 mph in 10 seconds. Explicitly by answering the following

(a) What is the kg equivalance of 4000 Ib?

(b) What is the m/s equivalance of 60 mph?

(c) What is the acceleration in m/s2?

(d) What is the final kinetic energy?

(e) What is the average power in Watts?

(f) What is the average power in HP?