# A rocket with a satellite accelerates upward from the earth's surface. At 1.15 sec. after liftoff, the rocket clears the top of its launch platform, 63 m above the ground. What is the magnitude of the average velocity of the rocket for the 4.75 s flight?

##### 2 Answers

The average velocity of the rocket during the first 4.75s is 226.75m/s upwards.

#### Explanation:

Note: I'm assuming a constant acceleration for this problem.

We can solve this problem using basic kinematics.

Since the rocket was at rest when launched, our initial velocity is

Find the acceleration of the rocket using our first set of info

Find the final velocity of the rocket at 4.75s

Find the average velocity of the rocket for the first 4.75s

Since we're looking for an average velocity and not an average speed we also need to include a direction, so our final answer is

#### Explanation:

**FULL QUESTION**

*A rocket with a satellite accelerates upward from the Earth's surface. At 1.15 sec. after liftoff, the rocket clears the top of its launch platform, 63 m above the ground. After an additional 4.75 sec, it is 1.00 km above the ground.*

*What is the magnitude of the average velocity of the rocket for the 4.75 s flight?*

So, you know that your rocket covers **63 m** in **1.15 s**, which means that you can determine the speed with which it *clears the platform* by using

Since the rocket started at rest, its initial velocity will be equal to **zero**. The acceleration of the rocket for the first **1.15 s** of flight will be

The rocket's velocity **after** 1.15 s of flight is

Now, you know that after **an additional** 4.75 seconds, the rocket is at a height of 1.00 km above the ground.

This means that it covered, in 4.75 seconds of flight, an additional

Use this distance and the flight time to determine its acceleration for the second portion of the flight

This means tha the speed of the rocket **after** the second part of its flight will be

Therefore, the *magnitude* of the average velocity is