<h2>
Its velocity when it crosses the finish line is 119.40 m/s</h2>
Explanation:
We have equation of motion s = ut + 0.5 at²
Initial velocity, u = 0 m/s
Acceleration, a = ?
Time, t = 6.70 s
Displacement, s = 1/4 mi = 0.25 mi = 400 m
Substituting
s = ut + 0.5 at²
400 = 0 x 6.70 + 0.5 x a x 6.70²
a = 17.82 m/s²
Now we have equation of motion v = u + at
Initial velocity, u = 0 m/s
Final velocity, v = ?
Time, t = 6.7 s
Acceleration, a = 17.82 m/s²
Substituting
v = u + at
v = 0 + 17.82 x 6.7
v = 119.40 m/s
Its velocity when it crosses the finish line is 119.40 m/s
You have said that 15cm³ of gold weighs 2.8N. So I may infer that each cm³
of gold weighs about 0.19N. When I compare that figure with the 0.13N per cm³
of mercury, it becomes immediately apparent that the gold is more dense than
mercury. Therefore, the sample of gold, no matter what its size or weight, will
displace its total volume of mercury, and will go on to sink entirely beneath the
waves in the mercury.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The distance which the car skid is 
Explanation:
From the question we are told that
The initial velocity of the car is 
The coefficient of kinetic friction is 
According to the law of energy conservation
The initial Mechanical Energy = The final Mechanical Energy
The initial mechanical energy is mathematically represented as

where KE is the initial kinetic energy which is mathematically represented as

And PE is the initial potential energy which is zero given that the car is on the ground
Now

Where
is the work which friction exerted on the car which is mathematically represented as

Where
is the distance covered by the car before it slowed down

=> 
Questions that can be answered by doing the experiment and making observations scientifically:
1). How long will it take to perform the complete experiment ?
2). Will it be daytime or night-time when the experiment begins ?
3). What will be the range of outdoor temperatures during the experiment ?
4). How many times will progress of the experiment be suspended in order to take phone calls ?
Predicting the volume of a gas, given its temperature and pressure p<span>roperties.</span>