# Physics virgin is this how I do it?

#### noodle21

A truck on a straight road starts from rest accelerating at 2.0 m/s2 until it reaches a speed of 20 m/s. Then the truck travels for 20 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional 5.0 s. (a) How long is the truck in motion? (b) What is the average velocity of the truck for the motion described?

My answers: (a) From rest to speed of 20 m/s it takes 10 s. Add 20 s. Add 5.0 s.... equals 35 s.

(b) I know average velocity is displacement divided by time. But, how do I calculate the displacement???

Related Introductory Physics Homework Help News on Phys.org

#### gnome

Calculate the displacements from the 3 segments of the trip separately. I assume you've come across a formula to calculate the distance traveled during constant acceleration...

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving