# Questions on Acceleration

• Raza
In summary, the car can reach a maximum speed of 150km/hr. It can accelerate at 5km/hr2 for a total of 25km/hr. It will take 5 hours for the car to cover 75km.

#### Raza

Okay, Can someone do these for me so I can understand acceleration:

My car can reach a maximum speed of 150km/hr. And my car can acclerate at 5km/hr2. How long will it take for my car to reach 150km/hr from rest.
I know acceleration is the velocity of the velocity and the eqn for acceleration but I don't know how it works.

Raza said:
My car can reach a maximum speed of 150km/hr. And my car can acclerate at 5km/hr2. How long will it take for my car to reach 150km/hr from rest.
From the definition of acceleration as the rate of change of velocity, the average acceleration will equal the change in velocity divided by the time:
a = (Vf - Vi)/t or Vf = Vi + at

Plugging in your values and solving for time gives: t = 30 hr.

So in 1 hour, it went from 0km/hr to 5km/hr. And in the 2nd, it went to 10km\hr. In 5 hours, how much distance did it cover?

At the end of 5 hours, its speed will be 25 km/hr. During those 5 hours the average speed, since it started from rest, is 12.5 km/hr. Use that speed to calculate the distance: 62.5 km.

1hr=5km/hr
2hr=10km/hr
3hr=15km/hr
4hr=20km/hr
5hr=25km/hr
5+10+15+20+25=75
75/5=15km\hr
at the end of 5hr, it will be 15km\hr x 5hr, which is 75km.

Raza said:
1hr=5km/hr
2hr=10km/hr
3hr=15km/hr
4hr=20km/hr
5hr=25km/hr
These are the speeds at those times. So?
5+10+15+20+25=75
What's this supposed to represent? Not the distance travel in each hour, I hope.

If that's what you're doing, start by working out the distance traveled in the first hour. Hint: It's not 5 km.

(I'm going to split off this discussion into a separate thread in "Intro Phys".)

## 1. What is acceleration?

Acceleration is the rate of change of velocity with respect to time. It is a vector quantity, meaning it has both magnitude and direction.

## 2. What is the formula for acceleration?

The formula for acceleration is: a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

## 3. How is acceleration related to force?

According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. This can be expressed as: F = ma, where F is force, m is mass, and a is acceleration.

## 4. What is the difference between average acceleration and instantaneous acceleration?

Average acceleration is the average rate of change of velocity over a given time interval, while instantaneous acceleration is the acceleration at a specific moment in time. Average acceleration can be calculated by dividing the change in velocity by the change in time, while instantaneous acceleration can be found by taking the derivative of the velocity function with respect to time.

## 5. How does acceleration affect motion?

Acceleration affects motion by changing an object's velocity. If the acceleration is in the same direction as the velocity, the object's speed will increase. If the acceleration is in the opposite direction, the object's speed will decrease. A change in direction of acceleration can also cause a change in the direction of motion.