Answer:
a) 0 J
b) 0.92J
Explanation:
The work is defined as:
because the normal force is perpendicular to the displacement the work done for it is zero.
The force because of frictions has an angle of 180 degrees because it is opposite to the motion, so:
The new acceleration is c) 18m/s/s
Explanation:
Net force, mass and acceleration of an object are related by Newton's second law of motion:
where
F is the net force on the object
m is its mass
a is its acceleration
In the first trial of this problem, a net force of is applied to the object, causing an acceleration of
Calling the mass of the object 'm', this means that
[N] (1)
In the second trial, the force applied is , so we have
where a' is the new acceleration. Substituting (1) into the second equation, we find:
This is because the acceleration is directly proportional to the force applied: therefore, if the force applied doubled, the acceleration doubles as well.
Learn more about Newton's second law:
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Answer:
The dog catches up with the man 6.1714m later.
Explanation:
The first thing to take into account is the speed formula. It is , where v is speed, d is distance and t is time. From this formula, we can get the distance formula by finding d, it is
Now, the distance equation for the man would be:
The distance equation for the dog would be obtained by the same way with just a little detail. The dog takes off running 1.8s after the man did. So, in the equation we must subtract 1.8 from t.
For a better understanding, at t=1.8 the dog must be in d=0. Let's verify:
Now, for finding how far they have each traveled when the dog catches up with the man we must match the equations of each one.
The result obtained previously means that the dog catches up with the man 3.8571s after the man started running.
That value is used in the man's distance equation.
Finally, the dog catches up with the man 6.1714m later.
This one is also using pre-conventional moral reasoning.