Find displacement, time and velocity

• kari82
In summary, a rocket takes off vertically from the launchpad with a constant upward acceleration of 2.25 m/s2. At 15.4 s after blastoff, the engines fail and the only force acting on the rocket is gravity. The maximum height the rocket will reach above the launchpad is 266.8m and it will be moving at a velocity of -72.3m/s right before it crashes onto the launchpad. To calculate the time it takes for the rocket to crash, we can use the equation v = u + at, where v is the final velocity (which we know is -72.3m/s), u is the initial velocity (which we know is 0m/s), and a is
kari82
A rocket takes off vertically from the launchpad with no initial velocity but a constant upward acceleration of 2.25 m/s2. At 15.4 s after blastoff, the engines fail completely so the only force on the rocket from then on is the pull of gravity.
(a) What is the maximum height the rocket will reach above the launchpad?
(b) How fast is the rocket moving at the instant before it crashes onto the launchpad?
(c) How longer after engine failure does it take for the rocket to crash onto the launchpad?

a)
deltay=vi(t)+1/2(a)(t)^2
deltay=0(15.4)+1/2(2.25m/s^2)(15.4s^2)
deltay=266.8m

b)Vf^2=vi^2+2(g)(deltay)
vf=+/-squareroot(2(-9.8m/s^2)(-266.8m))
vf=-72.3m/s

Can anyone tell me if what I'm doing is correct? and can i get a hint on how to solve question (c)?

Thanks!

v= u + at
and you said that the maximum velocity the rocket reaches is 72.3ms
the rocket from it's max height is accelerating towards Earth at a speed of 9.81ms.

there's your two values. just plug them into the equation.

Thank you!

What is displacement and how is it calculated?

Displacement is the distance and direction of an object's change in position. It is calculated by subtracting the initial position from the final position.

How is time related to displacement and velocity?

Time is a crucial factor in calculating displacement and velocity. Displacement is dependent on both the distance an object has moved and the time it took to move that distance. Velocity is the rate of change of displacement over time.

What is the formula for calculating displacement?

The formula for calculating displacement is:
Displacement (d) = Final position (xf) - Initial position (xi)

How do you find velocity from displacement and time?

Velocity is calculated by dividing the displacement by the time taken:
Velocity (v) = Displacement (d) / Time (t)

What are some common units for displacement, time, and velocity?

Displacement is typically measured in meters (m) or kilometers (km), time is measured in seconds (s) or hours (h), and velocity is measured in meters per second (m/s) or kilometers per hour (km/h).

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