The 1350-kg car has a velocity of 24 km/h up the 8-percent grade when the driver applies more power for 18 s to bring the car up to a speed of 65 km/h. Calculate the time average F of the total force tangent to the road exerted on the tires during the 18 s. Treat the car as a particle and neglect air resistance.

Explanation:

We shall apply concept of impulse to solve the problem  .

Impulse = force x time

impulse = change in momentum

force x time = change in momentum

initial speed u = 24 km/h = 6.67 m /s

final speed v = 65 km/h = 18.05 m /s

change in momentum = m v - mu

= m ( v-u )

= 1350 ( 18.05 - 6.67 )

= 15363 kg m/s

F x 18 = 15363

F = 853.5 N .

maria has a savings account that is earning simple interest. if she started with $200 in the account and has earned a total of $8 in interest in two years, what is the rate of the account? use the formula  .