# Homework Help: 3 acceleration questions

1. Mar 28, 2006

### kaaan

Hey all,

Im in grade 10 and we were learning the basics of physics, we had 3 acceleration questions that we had to answer for homework and im not sure how to do them. any help?

1) "while at a car rental facility, the agent gives you a choice between 2 cars for the same price. Car A accelerates from REST to 100km/h in 8.0s. Car B takes 6s in the same test. Since you like fastt cars, you want the car with the greater acceleration. Which car would you choose? car A or Car B? Prove it."

2) "Find the accleration, in m/s/s, of an airplane as it comes to a stop after landing. The airplane comes to a full stop from an intial velocity of 200 km/h [East] in 45 seconds. How far did the airplane travel as it slowed down."

3) "You meet up with your friend during your travels and decide to have a quick race on your bicycles. You start from the same direction and from the same place. You accelerate at 4 m/s/s for 10s up to your maximum speed. You then cycle at this speed for another 10s. Your friend accelerated at 5m/s/s for 20s. Who was ahead at the end of 20s and by how much."

Thanks and Regards,

Kaan

2. Mar 28, 2006

### tony873004

Do you know the formula for acceleration? For a hint, look at the units you gave in #2, m/s/s which can also be written m/s2.

3. Mar 28, 2006

### kaaan

yea, the formula is a = v1 - v2/ t or a= v/t

4. Mar 29, 2006

### Hootenanny

Staff Emeritus
That's all you need to know to answer the question, you have the initial and final velocities and you also have the time taken.

Just a quick note on your notation as velocity is change in velocity with respect to time it should be written as;

$$a = \frac{\Delta v}{\Delta t} = \frac{dv}{dt}$$

-Hoot