Acceleration Unit 9.1

velocity does not change velocity changes

speed direction A change in velocity includes _________ of an object changes _____________ of an object changes speed direction

Dn = nf-ni = 39-39 = 0 km/h Dn = nf-ni = -39-(-39) = 0 km/h

Dn = nf-ni = 39-0 = 39 km/h increases same direction Dn = nf-ni = -39-0 = -39 km/h + or - Dn = nf-ni = 0-60 = -60 km/h decreases opposite direction Dn = nf-ni = 0-(-60) = 60 km/h + or -

Dn = nf-ni = -50-60 = -110 km/h

Dn = nf-ni = -5.4 m/s – (-1.2 m/s) = - 4.2 m/s Dn = nf-ni Practice: What is the change in velocity for a man that starts walking at 1.2 m/s south and speeds up to 5.4 m/s south? What is the change in velocity for a ball thrown up into to the air with an initial velocity of 15 m/s up and the ball comes back down with a final velocity of 12 m/s down? Dn = nf-ni = -5.4 m/s – (-1.2 m/s) = - 4.2 m/s Dn = nf-ni = -12 m/s – 15 m/s = - 27 m/s

velocity acceleration Ddisplacement Dvelocity m/s2

increasing constant decreasing positive uniform positive

positive negative negative positive slowing slowing positive negative decelerating slowing slowing decelerating positive negative positive negative accelerating speeding accelerating speeding