Name:

# Newton's 2nd Law Rockets mit Gravity

If we fire a rocket vertically, its acceleration will be a bit less since it must struggle against gravity. For vertical ascent (neglecting air resistance):

- a
_{rocket}= F_{total}÷ m_{rocket}

If the rocket moves vertically, it sees (experiences) two forces:

- the upward thrust of 120 Newtons
- the weight of the rocket
- weight = (rocket's mass) · (accel of gravity)
- weight = 1.5kg · 9.8m/s
^{2} - weight ≈ 15N

## Solution:

- State the unknown:
**Acceleration** - State the givens:
**Force and Mass** - State the equation you plan to use:
**Acceleration = Force ÷ Mass** - Plug in values with units of measure:
**Acceleration = (120N – 15N) ÷ 1.5kg** - State your answer:
**70 m/s**^{2}

## Your Turn

A water bottle rocket has a mass of 0.248 kilograms. On Earth, this is a weight of 2.43 Newtons. When the water sprays out the bottom of the bottle rocket, it creates a starting thrust of 77 Newtons. Calculate the water rocket’s starting acceleration:

### Solution:

- State the unknown:
- State the givens:
- State the equation you plan to use:
- Plug in values with units of measure:
- State your answer:

### Solution:

- State the unknown:
**Acceleration** - State the givens:
**Force and Mass** - State the equation you plan to use:
**Acceleration = Force ÷ Mass** - Plug in values with units of measure:
**Acceleration = (77N – 2.43N) ÷ 0.248kg** **State your answer:****300m/s**^{2}