Wednesday

April 23, 2014

April 23, 2014

Posted by **Danny** on Saturday, January 11, 2014 at 10:29pm.

A) What is the acceleration? (m/s^2)

B) What is its speed after deceleration? (km/h)

A ANS = -.805m/s^2

B ANS = 52km

s = 450m

t = 20 seconds

u = 110km/h*1000m/km /60s/min*60 min/h

u = 110000/ 3600

u = 30.55

A) s = ut + 1/2 at^2

a = s - ut/ 1/2 * t^2

a = 450m - 30.55 * 20 sec/ 1/2 * 20^2

a = 450 - 611/ 1/2 * 400

a = -161/ 200

a = -.805m/s^2

I get stuck trying to figure out how to use the formula to get the answer to B which is 52 km.

I believe I would start with the formula: s = v + u/ 2 *t.

I would really appreciate the help with the second part of the question.

Thank you.

- Physics -
**Elena**, Sunday, January 12, 2014 at 3:01amv= v₀+at=30.55-0.805•20=14.5 m/s =14.5•3600/100=52.04 km/h

**Related Questions**

Physics - A train traveling at a speed of 110 km/h uniformly decelerates for 20 ...

physics - A red train traveling at 72 km/h and a green train traveling at 144 km...

physics - A red train traveling at 72 km/h and a green train traveling at 144 ...

Physics - A train travels 84 km/h when it reaches a slower train 47 meters ahead...

Physics - A train travels 84 km/h when it reaches a slower train 47 meters ahead...

Physics - A train travels 84 km/h when it reaches a slower train 47 meters ahead...

Math - I have figured the equation for this word problem Train A is traveling ...

algebra - Train A and B are traveling in the same direction on parallel tracks. ...

physics - A passenger train is traveling at 30 m/s when the engineer sees a ...

ALGEBRA-MAT117 - Trains A & B are traveling if the same direction on parallel ...