Answer:

And solving for a we got:


Explanation:
For this case we have an illustration for the problem on the figure attached.
And we can solve this problem analyzing each one of the runner. Let's begin with Mark
Mark
For this case we know that
and th velocity is constant. The distance from Mark and the finish line is 
Since the velocity is constant we can create the following relation:

And solving for
we got:

So then Mark will nd the race after 5.71 seconds
Paul
We know that the initial velocity for Paul is given
we also know that the total distance between Paul and the finish line is 25 m and we want to find the acceleration that Paul needs to apply in order to tie the race, and Paul have 5.71 sconds in order to reach the finish line.
We can use this formula in order to find the acceleration (because we assume that the acceleration is constant) that he needs to apply:

And since
we have this:

And if we replace we have this:

And solving for a we got:


And the final velocity for Paul using this acceleration would be:

If an object is moving with a constant velocity, then by definition it has zero acceleration. So there is no net force acting on the object. The total work done on the object is thus 0 (that's not to say that there isn't work done by individual forces on the object, but the sum is 0 ).
Answer:
8.1Ns
Explanation:
Impulse is expressed as the product of Force and time
Impulse = Ft
F is the force = 180N
Get the time using the equation of motion
v = u+at
18 = 0+F/m(t)
18 = 180/0.45(t)
18 = 400t
t = 18/400 secs
Recall that;
Impulse = Ft
Impulse = 180×18/400
Impulse = 8.1Ns
Hence the impulse imparted to the ball is 8.1Ns
The string that will break first depends on the weight of the block or bar subjected to such string.
According to Hook's law, the force applied to an elastic material is directly proportional to the extension of the material.
F= kx
where;
- <em>F is the force applied to the object = weight of the object</em>
For given two identical strings, the string that will break first depends on the mass of the bar and the block.
- If the bar is heavier than the block, then the string subjected to the bar will break first.
- On the other hand, if the block is heavier than the bar, then the string subjected to the block will break first.
Thus, the string that will break first depends on the weight of the block or bar subjected to such string.
Learn more here:brainly.com/question/4404276