Respuesta :
Answer:
Explanation:
let force exerted by engine be F.Net force =( F-400)N, applying newton law
F-400 = 1.5 x 10³x18 =27000 ,
F = 27400 N.
velocity after 12 s = 0 + 18 x 12 = 216 m/s
Average velocity = (0 + 216 )/2 = 108 m/s
Average power = force x average velocity = 27400 x 108 = 29.6 10⁵ W .⁶
b) At 12 s , velocity = 216 m/s
Instantaneous power = velocity x force = 216 x 27400 = 59.2 x 10⁶ W.
Answer:
Part a)
[tex]Power = 23850 W[/tex]
Part b)
[tex]P = 47700 W[/tex]
Explanation:
Part a)
As we know that the acceleration of the object is given as rate of change in velocity
[tex]a = \frac{dv}{dt}[/tex]
[tex]a = \frac{18 - 0}{12}[/tex]
[tex]a = 1.5 m/s^2[/tex]
now we know that
[tex]F_{net} = ma[/tex]
[tex]F - F_{air} = ma[/tex]
[tex]F - 400 = (1.50 \times 10^3)(1.5)[/tex]
[tex]F = 2650 N[/tex]
now the work done by the engine
[tex]W = F.d[/tex]
here distance covered by the engine is given as
[tex]d = \frac{v_f + v_i}{2} t[/tex]
[tex]d = \frac{18 + 0}{2} (12)[/tex]
[tex]d = 108 m[/tex]
now we have
[tex]Power = \frac{Work}{time}[/tex]
[tex]Power = \frac{2650 \times 108}{12}[/tex]
[tex]Power = 23850 W[/tex]
Part b)
Instantaneous power is given as
[tex]P = \frac{dW}{dt}[/tex]
[tex]P = F.v[/tex]
[tex]P = (2650)(18)[/tex]
[tex]P = 47700 W[/tex]
