Answer:
46.4 s
Explanation:
5 minutes = 60 * 5 = 300 seconds
Let g = 9.8 m/s2. And 
be the slope of the road, s be the distance of the road, a be the acceleration generated by Rob, 3a/4 is the acceleration generated by Jim . Both of their motions are subjected to parallel component of the gravitational acceleration 
Rob equation of motion can be modeled as s = a_Rt_R^2/2 = a300^2/2 = 45000a[/tex]
Jim equation of motion is 
As both of them cover the same distance
So Jim should start 346.4 – 300 = 46.4 seconds earlier than Rob in other to reach the end at the same time
Answer:
"It will be more than the speed of sound waves in air at 20*C and water at 20*C."
Explanation:
Speed of sound in a medium depends upon the density and elasticity of the medium.
If the elasticity of a medium is greater and the density of that medium is lower, sound will travel faster. Although density is also a factor but the major factor is Elasticity.
Hence, sound travel faster in solids than in liquids and even slower in gases due to elasticity difference.
That is why the speed of sound in glass will be more than the speed of sound waves in air at 20*C and water at 20*C.
