A car moving at 4.5 m/s accelerates at 2.5 m/s2 (The two is squared) After 7s, it will be moving how fast?

The formula is

V = final velocity = initial velocity U + (acceleration a * time duration t)

V = U + a t

= 4.5 m/s + 2.5 m/sec² * 7 sec = 4.5 + 17.5 = 22 m / sec

Acceleration means, every second the velocity or speed increases by that amount. Here it is 2.5. After one second velocity become 2.5 m/s more. after 2 seconds it is 5 m/s more. after 3 seconds, speed is 7.5 m/s more than at start. Like this after 7 seconds, the speed is 7 * 2.5 higher than at the beginning. so computer the total.