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2
votes
3answers
109 views

What happens to $P = F × v$ for a car moving on a frictionless surface and in vacuum?

I'm considering a scenario in which a car with an engine capable of producing maximum power of 200 hp is moving on a frictionless surface and in vacuum. Since no work is lost due to friction or air ...
0
votes
1answer
69 views

Force exerted by a motor, velocity, and friction

Some motor make an object move on a surface very slowly. One can write at steady state : $F_{motor}-F_{friction}=0$. The friction is supposed to come from the surface so : $F_{motor}-\mu_s m g=0$ with ...
-1
votes
1answer
70 views

When and how do we use the formula Power = force X velocity?

I'm unable to understand the solution given in this book mine... Why are we adding the resistive force? In fact, i would really appreciate if someone explains the question to me, I'm really struggling ...
0
votes
2answers
191 views

Propulsive Power, Thrust and Velocity

If my rocket requires thrust $T$ to maintain a velocity $v$, the propulsive power can be calculated using $$P=Tv$$ Assuming the same friction (so the required thrust to maintain the velocity doesn't ...
0
votes
0answers
32 views

How to increase power in a geared system using P = (omega)(torque)

Could someone give me a basic, intuitive explanation on how to increase power in a geared system using the P = omega*torque formula? By geared system I mean two connected gears, where the first one ...
2
votes
1answer
100 views

What assumptions would I have to make to rigorously prove power equals force dotted with velocity, $P=\mathbf{F}\cdot\mathbf{v}$?

$\newcommand{\F}{\mathbf{F}}$$\newcommand{\r}{\mathbf{r}}$$\newcommand{\v}{\mathbf{v}}$$\newcommand{\d}[2]{ \frac{ d #1 }{ d #2 }}$ There’s a well-known known formula for the power $P$ exerted on a ...
1
vote
3answers
189 views

What does the equation $P=\vec{F}\cdot \vec{v}$ really mean?

Let's say that we have a car travelling at a constant velocity (V) on a flat plane , let's assume that it's applied force or the force applied from its engine ( Fapp ) balances the frictional force ( ...
1
vote
2answers
234 views

Velocity over time applying constant power and considering air drag

I wanted to understand how velocity changes over time when applying a constant power to a body of mass $m$. I figured out that in this case, since $$P=d/dt(KE)=d/dt(\frac{1}{2}mv^2),$$ integrating I ...
-1
votes
1answer
827 views

What does $P = Fv$ mean? [closed]

The engine of a car is developing a power of 90kW when it is moving on a horizontal road at a constant speed of 100 km h−1. Estimate the total horizontal force opposing the motion of the car. I ...
0
votes
1answer
983 views

Calculating estimated HP from velocity, auto weight, and constant acceleration

I am working on a simulation program that runs theoretical performances of different cars and was wondering if there is a way to estimate the HP at any running RPM? the problem is (and this may be me ...
2
votes
1answer
826 views

Eddy Currents: Relationships between thickness and deceleration

This is probably a question with a very simple answer, but I want to make sure before I write too much. I'm doing an investigation on Electromagnetic fields, in particular eddy currents and how they ...
0
votes
3answers
205 views

I'm having trouble wrapping my head around force, and thus acceleration, diminishing with a higher velocity when using a constant power

Here is an hypothetical situation I thought about that I don't understand. Let's say I have 2 identical rockets with a fixed power. These rockets start to race in the same direction using the full ...
7
votes
6answers
7k views

When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?

Consider these two situations when driving on a long straight road uphill: Starting at a high velocity $v_h$, which the car is able to maintain. Starting at a lower velocity $v_l$, and then trying to ...
0
votes
1answer
763 views

Power, Force Velocity

In any case, if the force and power is constant , does velocity also need to be constant? If no, can you tell me a case. Further can this be extended for non-rigid bodies.