If a car can go from 0 to 60 mi/hr in 8.0 seconds, what would be its final speed after 5.0 seconds if its starting speed were 50 mi/hr?
Answer (3)
v 1 = 60 h mi t 1 = 8.0 s = 3600 8 h = 450 1 h − − − − − − − − − − − − − − a = t v a = 450 1 60 h 2 mi = 27000 h 2 mi − − − − − − − − − − − − − − v o = 50 h mi t = 5.0 s = 3600 5 h = 720 1 h − − − − − − − − − − − − − −
v = v o + a t v = 50 h mi + 27000 h 2 mi ⋅ 720 1 h = 50 h mi + 37.5 h mi = 87.5 h mi ← A n s w er
a = t V ⇒ a = 8 [ s ] 60 [ mi / h r ] t h e f ina l s p ee d a f t er 5.0 seco n d s V = 50 [ mi / h r ] + 5 [ s ] ⋅ 8 [ s ] 60 [ mi / h r ] = 50 [ mi / h r ] + 8 5 ⋅ 60 [ mi / h r ] = = 50 [ mi / h r ] + 37.5 [ mi / h r ] = 87.5 [ mi / h r ]
The final speed of the car after 5 seconds, starting from 50 mi/hr, is approximately 62.4 mi/hr. This was calculated using the initial speed, the acceleration from the initial condition, and the time duration. The acceleration was found to be 0.002083 mi/s² from the speed change from 0 to 60 mi/hr over 8 seconds.
;
