Question

A bottle rocket is launched vertically with an initial velocity of 20 m/sec.?
A) find the maximum height that the rocket will reach
B) the rocket did not explode and fell back to the ground, how long will it take to reach the ground?

Answer 1

ok so let's understand what's going on here. we know that it's leaving the launch pad with a velocity of 20 m/s and we can assume that this rocket is going straight up. So the rocket has velocity and is ascending because this velocity propels it in that direction but we know that what goes up must come down unless we're able to surpass escape velocity and manage to send your rocket into orbit but that's not the case here. gravity pulls your rocket down with an acceleration of -9.8 m/s^2 and we know that regular rockets will reach a point where the velocity becomes zero which is also where the rocket reaches it's highest point. knowing that we can look at this problem. we know v initial, we know v final and we know a. so using this we can find the height by using the kinematic equations.\[d=v_0t+\frac{1}{2}at^2\]\[v^2=v_0^2+2ad\]\[v=v_0+at\]\[d=\frac{v_0+v}{2}t\]looks like we can use equation 2 to find the maximum height of the rocket. just plug and chug and solve for d. now for time, look at the same list and we can see that equation 3 is perfect to find time. the same knowns can be used here.