Physics, 25.02.2020 00:55, iancuteodora30

Greg drove at a constant speed in a rainstorm for 287 miles. he took a break, and the rain stopped. he then drove 102 miles at a speed that was 10 miles per hour faster than his previous speed. If he drove for 9 hours, find the car's speed for each part of the trip

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answered: michaelswagout

38.22mph and 48.22mph

Explanation:

We first find Greg's average speed as follows. The average speed of a body is defined as the ratio of the total distance travelled by the body to the total time spent.

Total time spent, t = 9 hours

Total distance travelled, s = 287 + 102

s = 389 miles.

Hence the average speed is given thus;

$v_{avg}=\frac{389}{9}\\v_{avg}=43.22mph$

Let the speed for the first part of his journey be u and that for the last part be v, his average speed can also be expressed as follows;

$v_{avg}=\frac{u+v}{2}...........(1)$

Hence;

$43.22=\frac{u+v}{2}\\43.22*2=u+v\\86.44=u+v................(2)$

As stated in the problem, his speed for the final part of the journey was 10mph faster, therefore;

v=10 +u....................(3)

By substituting (3) into (2), we obtain the following;

$86.44=2u+10\\2u=86.44-10\\2u=76.44\\$

Hence,

$u=\frac{76.44}{2}\\u=38.22mph$

$v=10+u\\v=10+38.22\\v=48.22mph$

answered: Guest

It equals just about 6,300 km per hour each day an week

answered: Guest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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Greg drove at a constant speed in a rainstorm for 287 miles. he took a break, and the rain stopped....