Question

A car (m = 1302 kg) traveling along a road begins accelerating with a constant acceleration of 1.50 m/s2 in the direction of motion. After traveling 392 m at this acceleration, its speed is 35.0 m/s. Determine the kinetic energy of the car when it began accelerating.

Answer 1

First we will use the concepts of motion kinetics for which the final speed is defined as shown below,

$v_f^2=v_i^2+2as$

Here,

$v_f$= Final velocity

$v_i$= Initial velocity

a = Acceleration

s = Distance

Replacing,

$(35)^2 = v_i^2+2(1.5)(392)$

$v_i = 7m/s$

Using the conservation of energy for kinetic energy we have,

$KE = \frac{1}{2}mv_i^2$

$KE = \frac{1}{2}(1302)(7)^2$

$KE = 31900J$

Therefore the kinetic energy of the car is 31900J