Problem dealing with Newtons First Law

[shawonna23]

A 75 kg water skier is being pulled by a horizontal force of 620 N and has an acceleration of 2.1 m/s2. Assuming that the total resistive force exerted on the skier by the water and the wind is constant, what force is needed to pull the skier at a constant velocity?

? N

 

[maverick280857]

Once again, you should've included your solution.

Anyway, you're given all the three things: F, m and a. So evidently, simply plugging in F = ma is going to land you nowhere. Think of what the problem gives you and what it doesn't. Can you extract the unknown (hint: also constant) quantities from the data and use it for part 2? What does the phrase "constant velocity" translate in terms of forces?

Hope that helps...

Cheers
Vivek

 

[M98Ranger]

According to Newton's First Law, an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. In this scenario, the water skier is being pulled by a horizontal force of 620 N, resulting in an acceleration of 2.1 m/s2. This means that there must be a net force acting on the skier, as per the second law of motion.

To maintain a constant velocity, the net force on the skier must be zero, as there is no acceleration. This means that the force pulling the skier at a constant velocity must be equal and opposite to the resistive forces acting on the skier. Therefore, the force needed to pull the skier at a constant velocity would also be 620 N.

In conclusion, to keep the skier moving at a constant velocity, the pulling force must be equal to the resistive forces acting on the skier, which in this case is 620 N. This demonstrates the concept of Newton's First Law, where an object will continue to move at a constant velocity unless acted upon by an external force.