The English letter ‘a’ is used to denote acceleration and a avg stands for average acceleration
When you compare the velocity change over time, you get the rate of velocity change for a given unit of time or you get the value of average acceleration for that time interval.
So, Average acceleration = change in velocity/difference in time
aavg=ΔvΔt
aavg=v2−v1t2−t1
where, v1 = initial velocity
v2 = final velocity
t1 = time at the starting point
t2 = time at the end point
∆v and ∆t are change in velocity and time respectively for the part of the journey.
The slower the rate of velocity change or acceleration, smoother is your journey; the faster the rate of velocity change or acceleration your journey will be uncomfortable.
A train is running with a speed of 60 kilometer/second. At 12:05 p.m., the driver applies the brakes to stop the train at the platform at a constant rate. At 12:10 p.m. the train stops at the platform. What should be the rate of change of the velocity (acceleration) so that train stops in 5 minutes?
We have discussed the equation of average speed. Here we will apply the same equation and calculate the rate of change of velocity i.e. acceleration. The velocity of the train reduces to 0 km/hour from 60 km/hour.
Equation of average acceleration is,
aavg=ΔvΔt
aavg = (0-60) kilometer/hour / 5 minute
aavg = -12 km/hour/minute
This answer tells you that the speed of train must have slowed down at the rate of 12 km/hour/minute to stop it in five minutes.
A negative sign indicates slowing or retardation of the train.
If the train slows down at a constant rate of 12 km/hour/minute then we can represent it as:
Time (minutes)
0
1
2
3
4
5
Velocity (km/hour)
60
48
36
24
12
0
Table 8.3: Velocity versus Time
Here are few questions for you to answer:
Rating:
Confirm Finish Lesson: Lesson 8: Acceleration?
You will NOT be allowed to attempt Question again.
Calculating acceleration
The English letter ‘a’ is used to denote acceleration and a avg stands for average acceleration
When you compare the velocity change over time, you get the rate of velocity change for a given unit of time or you get the value of average acceleration for that time interval.
So, Average acceleration = change in velocity/difference in time
aavg=ΔvΔt
aavg=v2−v1t2−t1
where, v1 = initial velocity
v2 = final velocity
t1 = time at the starting point
t2 = time at the end point
∆v and ∆t are change in velocity and time respectively for the part of the journey.
The slower the rate of velocity change or acceleration, smoother is your journey; the faster the rate of velocity change or acceleration your journey will be uncomfortable.
We have discussed the equation of average speed. Here we will apply the same equation and calculate the rate of change of velocity i.e. acceleration. The velocity of the train reduces to 0 km/hour from 60 km/hour.
Equation of average acceleration is,
aavg=ΔvΔt
aavg = (0-60) kilometer/hour / 5 minute
aavg = -12 km/hour/minute
This answer tells you that the speed of train must have slowed down at the rate of 12 km/hour/minute to stop it in five minutes.
A negative sign indicates slowing or retardation of the train.
If the train slows down at a constant rate of 12 km/hour/minute then we can represent it as:
Time (minutes)
0
1
2
3
4
5
Velocity (km/hour)
60
48
36
24
12
0
Table 8.3: Velocity versus Time
Here are few questions for you to answer: