# Question relates to Degree and some other simple question.

1. May 7, 2012

### louis676

1. Marcia was driving her car at the constant speed of 19.2 m/s when she saw the light turn red. It took her .13 sec to hit the brakes, but then the car slowed at the constant rate of 6.2 m/s2 until it stopped. How much time did it take for the car to stop moving after the light turned red.? How far did the car travel until it stopped?
Did I plug in the right number for each symbol?

I am confuse of which equation to use and which question should I put .13s to.

First question:

V0 = 19.2 m/s
A = -6.2 m/s 2
Δt = ?

Δx=?

Δx = V0Δt + .5a(Δt)2

Second question:
V0 = 19.2 m/s
A = -6.2 m/s 2
Δt = .13 s

Δx=?

Δx = V0Δt + .5a(Δt)2

2. Standing on a flat roof of a 21 m high building, Ali threw a ball up at a 60 degree angle to the roof top. The speed of the ball was 25 m/s. When the ball left Ali’s outstretched hand the ball was 3.1 meters from the roof top. The ball eventually landed on the roof. High far was the ball from Ali?

I never work on question related to degree, so I am pretty lost on this one.
Vo = 25m/s
A = -9.8 m/s 2
Vf = 0 m/s
Δx = ?

3. Maxim was driving his car at 15 m/s when he pressed the gas pedal down to accelerate at 5.2 m/s2. How far did he travel in the next 2.5 seconds?

I think this is correct.
Δx = ?
V0 = 15 m/s
Δt = 2.5 s
A = -5.2 m/s 2

Δx = V0Δt + .5a(Δt)2

Δx = 15 m/s (2.5 s) – 5.2 m/s 2 (2.5 s 2)

Δx = 37.5 m – 32.5 m

Δx = 5m
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. May 8, 2012

Bump!

3. May 9, 2012

### azizlwl

1. Draw a velocity - time graph.
2. Not sure how the rooftop and roof configuration.
3. Why the acceleration is negative? Draw a velocity- time graph here too.

Last edited: May 9, 2012