A test rocket is fired straight up from rest with a net acceleration of 20 m/s 2

Question

A test rocket is fired straight up from rest with a net acceleration of 20 m/s2. After 4 seconds the motor turns off, but the rocket continues to coast upward. What maximum elevation does the rocket reach? Select one: a. 327 m b. 408 m c. 487 m d. 160 m e. 320 m A test rocket is fired straight up from rest with a net acceleration of 20 m/s2. After 4 seconds the motor turns off, but the rocket continues to coast upward. What maximum elevation does the rocket reach? Select one: a. 327 m b. 408 m c. 487 m d. 160 m e. 320 m Select one: a. 327 m b. 408 m c. 487 m d. 160 m e. 320 m a. 327 m b. 408 m c. 487 m d. 160 m e. 320 m

Explanation / Answer

initially net acceleration = 20 m/s^2
time = 4 seconds;
v = u + a*t
u = 0 ==> v = 20*4 = 80 m/s
s = u*t + .5 * a *t^2 ==> s = .5 * 20 * 16 = 160 meters
after 4 seconds , speed of rocket = 80 m/s
net acceleration = -9.8 m/s^2 ;
at maximum height v = 0
v = u + a*t ==> t = 80/9.8 = 8.16326531 seconds
s = u*t + .5 * a * t^2
s = 80* 8.16326531 + .5 * (-9.8)* 8.16326531^2 = 326.530612 meters
total height = 160 + 326.530612 = 486.530612 meters
maximum elevation = 486.530612 meters

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.