# Homework Help: Kinematics, need help conceptualizing

1. Sep 13, 2006

### phoizgood

I need help understanding this question. I dont need the answer or anything, I just want some help visualizing, whats going on, what do I need to know, how do I get there, etc. Am I being confusing?

Speedy Sue, driving at 30.0 m/s, enters a one-lane tunnel. She then observes a slow-moving van 155 m ahead traveling at 5.00 m/s. Sue applies her brakes but can accelerate only at -2.00 m/s^2 because the road is wet. Will there be a collision? If yes, determine how far into the tunnel and at what time the collision occurs. If no, determine the distance of cloest approach between Sue's car and the van.

Am I suppose to find when the two car is same distance or something?? Please help me.

2. Sep 13, 2006

### Andrew Mason

What is the condition for a collision?

If you plot speed vs. time for each vehicle, the area under the graph represents what quantity? Are those areas ever equal?

AM

3. Sep 13, 2006

### phoizgood

"What is the condition for a collision?"

When the two car's X_final equals to each other? correct?

"If you plot speed vs. time for each vehicle, the area under the graph represents what quantity? Are those areas ever equal?"

speed vs time graph, area under graph is acceleration right? so what does having equal acceleration fits in this equation?

4. Sep 13, 2006

### mbrmbrg

Correct.

No.

Without calculus:

Area=(length)(height)
On a speed vs time graph, length is time and height is speed.
What happens to the units when you multiply time by speed? What units do you end up with? What are those units used to measure?