A car starts from rest and accelerates uniformly to a speed of 72 km per hour over a distance of 500m. calculate acceleration

0.4 m/s^2 or 5184 km/h^2

Explanation:

To find the acceleration, given the inicial and final speed of the car, we can use the Torricelli's formula:

V^2 = Vo^2 + 2*a*D

Where V is the final speed, Vo is the inicial speed, a is the acceleration and D is the distance travelled. So, with V = 72 km/h, Vo = 0 (starts from rest) and D = 0.5 km, we have:

72^2 = 0 ^2 + 2*a*0.5

a = 72^2 = 5184 km/h^2

For an acceleration in m/s^2, we should use the speed in meters per second (72 / 3.6 = 20 m/s) and the distance in meters (D = 500):

20^2 = 0^2 + 2*a*500

400 = 1000a

a = 0.4 m/s^2

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.