Question

What is the kinetic energy in joules of a 1000kg automobile traveling at 90 km/hr?

Answer 1

The kinetic energy of a 1000kg automobile moving at 90 km/hr can be calculated by first converting the speed to m/s, which results in approximately 25 m/s, and then applying the kinetic energy formula KE = 0.5 × m × v2 to get 312500 J or 312.5 kJ.

Step-by-step explanation:

The kinetic energy of an object can be calculated using the formula KE = 0.5 × m × v2, where KE is kinetic energy in joules (J), m is mass in kilograms (kg), and v is velocity in meters per second (m/s). To find the kinetic energy of a 1000kg automobile traveling at 90 km/hr, we first need to convert the velocity to meters per second. Since 1 km/hr is approximately 0.27778 m/s, 90 km/hr is equal to 90 × 0.27778 m/s, which is approximately 25 m/s.

Substituting the given values into the kinetic energy formula gives us:

KE = 0.5 × 1000 kg × (25 m/s)2

KE = 0.5 × 1000 × 625

KE = 312500 J, which is 312.5 kJ.

Therefore, the kinetic energy of the automobile is 312500 joules or 312.5 kilojoules.

Answer 2

Kinetic energy is given as,

K.E = 1/2 mv² -----(1)
Data Given:
Mass = m = 1000 kg

Velocity = v = 90 Km/h = (90 ×1000) / (1× 60 × 60) = 25 m/s

Putting values in equation 1,

K.E = 1/2 × 1000 Kg × (25)² m/s

K.E = 1/2 × 1000 Kg × 625 m/s

K.E = 312500 Kg m s⁻¹
Or,
K.E = 312500 J
Or,
K.E = 312.5 kJ