True or False: There is the same amount of water on earth today as there was when earth was formed.

An Olympic track runner starts from rest and has an acceleration of 2.4 m/s2 for 3.6 s, then has zero acceleration for the remai

rjkz [21]

Answer:

The runner's speed at the following times would remain 8.64 m/s.

Explanation:

Acceleration definition: Acceleration is rate of change in velocity of an object with respect to time.

In this case, after 3.6 seconds the acceleration is zero, it means that the velocity of the runner after 3.6 seconds is not changing and it will remain constant for the remainder of the race. Now, we have to find the velocity of the runner that he had after 3.6 seconds and that would be the runner's speed for the remainder of the race. For this we use first equation of motion.

First equation of motion: Vf = Vi + a×t

Vf stands for final velocity

Vi stands for initial velocity

a stands for acceleration

t stands for time

In the question, it is mentioned that the runner starts from rest so its initial velocity (Vi) will be 0 m/s.

The acceleration (a) is given as 2.4 m/s²

The time (t) is given as 3.6 s

Now put the values of Vi, a and t in first equation of motion

Vf = Vi + a×t

Vf = 0 + 2.4×3.6

Vf = 2.4×3.6

Vf = 8.64 m/s

So,the runner's speed at the following times would remain 8.64 m/s.

5 0

3 years ago

If two objects have the same mass, what determines the strength of the gravitational force between them? (4 points) Select one:

Evgen [1.6K]

According to this equation

F = G × m₁*m₂ ÷ r²

other than the mass, the distance also affects the gravitational force between two objects (same mass or not).

Therefore the correct answer is B. The distance between the objects

Future note* use formulas to help you figure these sort of questions out. (if they have a formula to begin with).

3 0

3 years ago

A police car is located 50 feet to the side of a straight road. A red car is driving along the road in the direction of the poli

NNADVOKAT [17]

Answer:74.33 feet per sec

Explanation:

Given

Police car is 50 feet side of road

Red car is 140 feet up the road

Distance between them is decreasing at the rate of 70 feet per sec

From figure

$x^2+y^2=z^2$

$z=\sqrt{140^2+50^2}$

z=148.66 feet

as the red car is moving

therefore its velocity magnitude is given by

$\frac{\mathrm{d} x}{\mathrm{d} t}$

$2x\times \frac{\mathrm{d} x}{\mathrm{d} t}+0=2z\frac{\mathrm{d} z}{\mathrm{d} t}$

$x\frac{\mathrm{d} x}{\mathrm{d} t}=z\frac{\mathrm{d} z}{\mathrm{d} t}$

$140\times \frac{\mathrm{d} x}{\mathrm{d} t}=148.66\times 70$

$\frac{\mathrm{d} x}{\mathrm{d} t}=74.33 feet\ per\ sec$

6 0

4 years ago

What are three key aerodynamics principles?

mafiozo [28]

Answer:

A

Explanation:

There are three basic forces in aerodynamics: acceleration, which moves an airplane forward; drag, which holds it back; and height, which keeps it airborne. Lift is generally explained by three theories: Bernoulli's principle, the Coanda effect, and Newton's third law of motion.

8 0

3 years ago

Consider the video tutorial you just watched. Suppose that we duplicate this experimental setup in an elevator. What will the sp

zloy xaker [14]

Explanation:

if the elevator is moving upward with the constant speed the spring scale will read 18 N which is the mass of each of the two blocks attached by separate springs to the scale at opposite ends.

4 0

3 years ago