Mastering Physics Homework Question?

An automobile traveling 95 km/h overtakes a 1.00 km -long train traveling in the same direction on a track parallel to the road.

1. If the train's speed is 75 km/h, how long does it take the car to pass it?

Express your answer to two significant figures and include the appropriate units.

Assume car is 5.00 m long approx.....overtaking is ended when the tail of the car reaches the front of the train

ΔS = 1000+5 = 1005 m

ΔV = (95-75)/3.6 = 5.5556 m/sec

time t = ΔS/ΔV = 1005/5.5556 = 180.90 sec

2. How far will the car have traveled in this time?

distance D = Vc*t = 95/3.6*180.90 = 4774 m

3. How long does it take the car to pass the train if the car and train are traveling in opposite directions?

ΔS = 1000+5 = 1005 m

ΔV = (95+75)/3.6 = 47.222 m/sec

time t = ΔS/ΔV = 1005/47.222 = 21.28 sec

4. How far will the car have traveled in this time?

distance D = Vc*t = 95/3.6*21.28 = 561.6 m

Hey This seems like a relatively simple components question. First you want to set up a free body diagram sowing tension and the force exerted by the bolt as well as gravity, all these should sum to zero since no acceleration is happening. I'd have to assume all the weight is on the rope and the bolt provides stability seeing as there is no enough there to assume otherwise. Therefore Fg=ma, and we know the m and a=9.81m/s^2. When you draw a diagram you will notice there is a triagle that appears out of the top of the sign, the rope and the place where the rope attaches to the wall. The long part is equal to f=ma, and you can figure out all of the angle simply by knowing that one is twenty and the other is 90. Use sin law to find the next component of tension, solve for the hypotenus using pythagorus and you are done. For the next part I'd have to say zero since the rope takes all the force and there is no acceleration in the horizontal direction.

car speed is 95 km/h. Train speed is 75 km/h. The speed difference is 95-75=20 km/h. Assume car length is negligible. To cover the distance of 1km, you need 1/20 hours= 3 minutes.

The distance covered by the car is

s= 95*1/20=4.5 km.

You can repeat this for the second part. Now add the speeds.

C=95t, T=75t but for the car to completely pass the train we need C to be 1km more than T so

95t=75t+1

25t=1

t=1/25

in hours this is .04 hours (144s)

...

C=95(.04)=3.8km

...

C=95t and T=-75t in essence this is the same as if the car were traveling at 170km/h and the train was stationary...and we want the car to travel the length of the 1km train so...

1=170t, t=h/170 (about 21 seconds...)

...

C=95/170=19km/34 (about 559m)