Corrections to Questions on Acceleration
1. A car changes its velocity by 30 m/s in 5 seconds, what is the acceleration of the car?
v=30m/s
t=5s
a=∆v/∆t
a=30/5
a=6m/s2
2. A bike starts from rest and accelerates to 20 m/s over a period of 6 seconds. What is the acceleration of the car?
v=20m/s
t=6s
a=∆v/∆t
a=20/6
a=3.33m/s2
3. A man moving at 2 m/s accelerates at a rate of 3 m/s2 for 2.5 seconds. What is the new velocity of the man?
a=3m/s2
t=2.5s
ax∆t=∆v
3x2.5=∆v
v=7.5m/s
a=v-u/∆t
3=v-2/2.5
V=9.5m/s
4. A car decelerates from 60 m/s to 20 m/s at a rate of -5 m/s2. How long does this deceleration take the car?
v= -40m/s
a= -5m/s2
t=∆v x a
t=-40x-5
t=200s
a=v-u/∆t
-5=20-60/t
t=8s