Okay guys so physics is confusing me to tears right now. I just need a little he

Question

Okay guys so physics is confusing me to tears right now. I just need a little help actually setting up how to find the solutions. So any help and explanations would be much appreciated! Here goes:

1.)The Voyager 1 spacecraft is expected to continue broadcasting data until at least 2020, when it will be some 14 billion miles from Earth.How long will it take Voyager's radio signals, traveling at the speed of light, to reach Earth from this distance?

2.)A space shuttle's main engines cut off 8.3min after launch, at which time the shuttle's speed is 7.7km/s.What is the shuttle's average acceleration during this interval?

3.)An airplane's takeoff speed is 360km/h.If its average acceleration is 2.9m/s2 , how much time is it accelerating down the runway before it lifts off?

4.)A car moving initially at 44mi/h begins decelerating at a constant rate 90ft short of a stoplight.If the car comes to a full stop just at the light, what is the magnitude of its acceleration?

Explanation / Answer

1)time=distance/speed

=14*10^9*1609.34/(3*10^8)

=7.51*10^4 s

2)acceleration be a.so,

v=u+at

or 7.7*10^3=a*8.3*60

or a=15.46 m/s^2

3)speed=360*5/18

=100 m/s

v^2=2as

or 100^2=2*2.9*s

or s=1724.14 m

4)speed=19.668 m/s

s=27.432

so a=v^2/2s

=19.668^2/(2*27.432)

=7.05 m/s^2

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