4. A car accelerates at 2.5 m/s^2, covers 4 km in 0.8 min. How fast was it moving at the beginning of the time interval? *​

Initial velocity, u = 23.33 m/s

Explanation:

Given the following data;

Acceleration = 2.5 m/s²

Distance = 4 km to meters = 4000 meters

Time = 0.8 mins to seconds = 0.8 * 60 = 48 seconds.

To find the initial velocity, we would use the second equation of motion;

Where;

S represents the displacement or height measured in meters.

u represents the initial velocity measured in meters per seconds.

t represents the time measured in seconds.

a represents acceleration measured in meters per seconds square.

Substituting into the equation, we have;

4000 = u*48 + ½*2.5*48²

4000 = 48u + 1.25*2304

4000 = 48u + 2880

48u = 4000 - 2880

48u = 1120

Initial velocity, u = 1120/48

Initial velocity, u = 23.33 m/s

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation: