#### acceleration (Noun “ack-SELL-er-AY-shun”)

This is the rate of change in speed over time. Speed ​​is the speed of something in a certain direction. Acceleration is when the speed changes. Since speed is both speed and direction, acceleration can also include speed and direction.

Accelerating accelerates. Turning left also speeds up. Even slowing down technically speeds up! How does this work? It’s still a change in speed – but in this case the acceleration is negative. Some people might call this delay. However, the delay only relates to a reduction in speed. Negative acceleration can be a decrease in speed, but also a change in direction – backwards instead of forwards.

Remember that acceleration and speed are not the same thing. Something can have a very high speed – like a jet flying in the air – and accelerate or decelerate very little. In other words, the aircraft has high speed and low acceleration. And a car can be stopped at a stop sign and then speeded down the street very quickly. That’s a small speed – the car is stopped, so the speed is zero – and a large acceleration or change in speed.

Acceleration is often used when scientists calculate force. This is the F in the equation F = ma (force equals mass times acceleration). Suppose a glass falls and hits the floor. The force with which it hits is equal to the mass of the glass multiplied by the acceleration when it falls. This is also the reason why a car accident at 8 kilometers per hour has far less force than an accident at 80 km / h. The negative acceleration when the car is stopped is much, much less at slower speeds.

#### In one sentence

Insects, so-called snipers, throw piss when they are being fed – with up to six times the acceleration that an astronaut feels at takeoff.

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