To calculate the kinetic energy and braking of a car, we need to consider the initial kinetic energy and the work done by the braking force to bring the car to rest.
Given: Mass of the car (m) = 1200 kg Initial velocity (u) = 25 m/s Final velocity (v) = 0 m/s (car comes to rest) Distance traveled during braking (d) = 40 m
First, let's calculate the initial kinetic energy (KE) of the car using the formula:
KE = (1/2) * m * u²
KE = (1/2) * 1200 * (25)²
KE = 375,000 Joules
Next, we can calculate the work done by the braking force. The work done is equal to the change in kinetic energy, which is given by:
Work (W) = ΔKE = KE_final - KE_initial
Since the final kinetic energy is zero when the car comes to rest:
Work (W) = -KE_initial
W = -375,000 Joules
Note that the negative sign indicates that work is done against the motion of the car (opposing the initial kinetic energy).
Therefore, the kinetic energy of the car is 375,000 Joules, and the work done by the braking force to bring the car to rest is -375,000 Joules.