---
title: "Speed, acceleration and momentum — free, runs in your browser"
description: "Velocity, acceleration, momentum, force and the equations of motion. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/physics-motion-calculator/
site: "At One Place"
---

# Speed, acceleration and momentum

Velocity, acceleration, momentum, force and the equations of motion.

## How it works

Solves the standard motion relationships: speed from distance and time, acceleration from change in velocity, momentum, force, and the SUVAT equations for constant acceleration.

Speed and velocity are not synonyms, and the distinction shows up in answers. Speed is a magnitude; velocity carries a direction. An object moving in a circle at constant speed is accelerating continuously, because its velocity is changing direction — which is why you feel pushed sideways in a turning car despite the speedometer not moving.

Force is mass times acceleration, so the same force produces very different accelerations on different masses. Momentum is mass times velocity and is conserved in collisions, which is why a small fast object and a large slow one can do comparable damage.

The SUVAT equations only hold under constant acceleration. Real falling objects hit terminal velocity as drag rises with speed, so the constant-acceleration answer overestimates badly for anything falling more than a few seconds.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### What is the difference between speed and velocity?

Speed is magnitude only; velocity includes direction. Something moving in a circle at constant speed is accelerating, because its direction changes.

### Do the SUVAT equations work for falling objects?

Only briefly. They assume constant acceleration, and real objects reach terminal velocity as air resistance grows with speed.

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## Sources

- Calculated on this page — At One Place (/about/)