If a car moving at 180km/h redues to 72km,what is the percentage change in kinetic energy.
To determine the percentage change in kinetic energy, we need to first find the initial and final kinetic energies.
The formula for kinetic energy is given by:
Kinetic Energy (KE) = (1/2) * mass * velocity^2
Since the mass of the car remains constant, we don't need to consider it in our calculation.
Let's calculate the initial and final kinetic energies:
Initial Velocity (Vi) = 180 km/h = 180,000 m/3600 s = 50 m/s
Final Velocity (Vf) = 72 km/h = 72,000 m/3600 s = 20 m/s
Initial Kinetic Energy (KEi) = (1/2) * Vi^2
= (1/2) * 50^2
= 1250 J
Final Kinetic Energy (KEf) = (1/2) * Vf^2
= (1/2) * 20^2
= 200 J
Now, we can calculate the percentage change in kinetic energy using the following formula:
Percentage Change = ((Final Value - Initial Value) / Initial Value) * 100
Percentage Change = ((200 - 1250) / 1250) * 100
= (-1050 / 1250) * 100
= -0.84 * 100
= -84%
Hence, the percentage change in kinetic energy is -84%. The negative sign indicates a decrease in kinetic energy.