For the constant negative acceleration graphs the initial displacement is negative and the initial velocity is positive. Question.

The acceleration is the (final velocity – initial velocity) ÷ time, which is -8 m/s ÷ 2 s = -4 m/s 2. The car has an acceleration of -4 m/s 2 . A negative acceleration is called a retardation .

At t 1, the angular velocity is zero, with a non-zero (negative) angular acceleration. At that time, the direction of rotation for BC is changing from CCW to CW. At t 2, the angular velocity is zero, ...