Question

The car is traveling at a constant speed v0 = 80 km/hr on the level portion of the road. When the 4-percent (tan q = 4/100) incline is encountered, the driver does not change the throttle setting and consequently the car decelerates at the constant rate g sin q. Determine the speed of the car: (a) 28 seconds after passing point A ,and (b) when s = 620 m.

Answer 1

Answer:

11.27 m /s

2.98 m / s.

Explanation:

80 km / h = 22.22 m /s

Tanq = 4 / 100

Sinq = .0399

Deceleration acting on inclined plane = g sinq

= 9.8 x .0399

= .3910

Initial speed u = 22.22 m/s

acceleration = - .3910 ms⁻²

v = u - a t

= 22.22 - .3910 x 28

= 22.22 - 10.95

= 11.27 m /s

b ) v² = u² - 2 a s

v² = ( 22.22) ² - 2 x .3910 x 620

= 493.7284 - 484.84

= 8.8884

v = 2.98 m / s.