contestada

A test rocket is launched vertically from ground level (y=0), at time t=0.0s. The rocket engine provides constant upward acceleration during the burn phase. At the instant of engine burnout, the rocket has to 49m and acquired velocity of 30m/s. How long the burn phase last?
A. 2.6
B. 2.3
C. 3.3
D. 3.6
E. 2.9

Respuesta :

LammettHash

From the definition of average velocity,

[tex]\bar v=\dfrac{\Delta y}{\Delta t}=\dfrac{49\,\mathrm m}t[/tex],

and the fact that constant acceleration means

[tex]\bar v=\dfrac{v_f+v_0}2=\dfrac{30\,\frac{\mathrm m}{\mathrm s}}2=15\,\dfrac{\mathrm m}{\mathrm s}[/tex]

we can solve for the time [tex]t[/tex]:

[tex]15\,\dfrac{\mathrm m}{\mathrm s}=\dfrac{49\,\mathrm m}t\implies t=3.3\,\mathrm s[/tex]

Otras preguntas