DOST Junior Level Science Scholarship (JLSS) Practice Exam

Acceleration is the rate at which velocity changes with time. Velocity tells how fast something is moving and in what direction, so any change in speed, a change in direction, or a combination of both is acceleration. Mathematically, it’s a = dv/dt, the change in velocity divided by the time over which that change occurs, with units of meters per second squared. For example, if a car speeds from 0 to 20 m/s in 4 seconds, its acceleration is 20/4 = 5 m/s^2. Even if the speed stays the same but the direction changes, such as a car turning in a circle at constant speed, the velocity is changing and there is acceleration toward the center of the circle. Speed is how fast something is moving, without direction. Velocity is speed with direction. Displacement is how far the object has moved from its starting point, regardless of the path taken. These are related ideas, but the term that describes how velocity changes over time is acceleration.