deceleration

Everyday

(science) Deceleration is slowing down; the rate at which something's speed gets smaller. tree →

In the lessons

In science, deceleration is the opposite of acceleration: when a car brakes or a ball rolls to a stop, it decelerates; friction and air resistance cause deceleration. In maths and physics, it can be measured in metres per second per second (m/s²). Seatbelts protect you during sudden deceleration in a crash.

Examples

• The car's deceleration was quick when the driver braked. tree →
• Friction causes the deceleration of the rolling ball. tree →
• A parachute causes a big deceleration. tree →
• Seatbelts protect you during sudden deceleration. tree →
• The rocket's deceleration let it land gently. tree →
• We measured the trolley's deceleration on the carpet. tree →

Note

Verb: decelerate. Opposite: acceleration. In a maths problem, a deceleration of 2 m/s every second means the speed drops by 2 each second (from 10 to 8, 6, 4…).