Amotorist driving at 25 meters/second decelerates to
15 meters/second. the combined mass of the vehicle and the driver is 1.5 × 10³ kilograms. what is the amount of mechanical work done by the vehicle?
a) 7.5 x 10^4 joules
b) 1.5 x 10^5 joules
c) 3.0 x 10^5 joules
d) 6.2 x 10^5 joules

Work done = 0.5*m*[(v2)^2 - (v1)^2]
where m is mass,
v2 and v1 are the velocities.

Given that m = 1.50 x 10^3 kg, v2 = -15 m/s (decelerates), v1 = 25 kg,

Work done = 0.5 * 1.50 x 10^3 * ((-15)^2 - 25^2) = 3 x 10^5 joules

Just ignore the negative value for the final result because work is a scalar quantity.