Applying Newton's 2nd Law: A Scientist's Guide

In summary, the conversation discusses how to approach a problem and provides instructions on how to calculate normal force, net force, and acceleration using Newton's laws and a free body diagram. The correct approach involves finding all forces in the x-axis and y-axis separately and using Newton's second law to calculate the net force and acceleration. The final calculation results in an acceleration of 3m/s^2.
  • #1
George2020
6
0
Homework Statement
A. A tractor pulls a 150 kg rock to the right with a force of 1200 N against a force of friction of 750 N [left].
• Calculate the force of gravity on the rock and the normal force of the ground on the rock.
• Draw a FBD of the rock, and determine the magnitude and direction of the net force acting on the rock.
• Use Newton’s second law to find the acceleration of the rock
Relevant Equations
Force(net)=mass x acceleration
Hi ,
How to approach the problem?
Thanks
 
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  • #2
Hi, and welcome to PF:welcome:

According to the rules of PF, you should show some effort of your own before we are allowed to help you. The problem gives you almost step by step instructions on what to do. What is it that you don't understand?

  • To calculate the normal force of the ground you ll have to apply Netwon's 2nd law in the y-axis (vertical direction) after you have found all the forces in this axis.
  • To calculate the magnitude and direction of the net force acting on the rock you have to draw an FBD where you draw all forces in the x-axis (horizontal direction) and all the forces in the y-axis, and then taking the sum of the forces in each axis separately. Then use pythagorean theorem if needed to combine the net force in the y-axis with the net force in the x-axis to find the total net force.
  • The problem implies there is motion only in the x-axis ("puls a 150kg rock to the right") so use that to your advantage. This effectively means that the acceleration along the y-axis is zero, while the acceleration along the x-axis ##a_x## might not be zero. Use Netwon's 2nd law ##\sum F_x=ma_x## in the x-axis to find the ##a_x##.
 
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Likes Lnewqban
  • #3
Thanks for input. Is this the correct approach.

Force of gravity = 150 x 9.8= 1470N[d]
Force Normal = -1470N

Force Net = Force applied +Force Friction
= 1200N +(-750N)
=450N

Force net=ma
a=Force net/mass
= 450N/150kg
= 3m/s sq.
 
  • #4
Yes i think you are correct.
 

Related to Applying Newton's 2nd Law: A Scientist's Guide

What is Newton's 2nd law application?

Newton's 2nd law application is a fundamental principle in physics that describes the relationship between an object's mass, acceleration, and the force applied to it. It states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

How do you calculate the acceleration of an object using Newton's 2nd law?

To calculate the acceleration of an object using Newton's 2nd law, you can use the formula: a = F/m, where a is the acceleration, F is the net force, and m is the mass of the object. This formula can also be rearranged to calculate the net force or mass of an object.

What are some real-life examples of Newton's 2nd law application?

Some common examples of Newton's 2nd law application include pushing a shopping cart, kicking a soccer ball, and riding a bike. In all of these scenarios, the force applied to the object (shopping cart, soccer ball, bike) determines its acceleration.

How does Newton's 2nd law apply to objects in motion?

Newton's 2nd law applies to objects in motion by explaining the relationship between an object's acceleration and the forces acting on it. If an object is already in motion, the net force acting on it will determine how its motion changes (i.e. if it speeds up, slows down, or changes direction).

Can Newton's 2nd law be applied to non-uniformly accelerating objects?

Yes, Newton's 2nd law can be applied to non-uniformly accelerating objects. In these cases, the net force acting on the object may change over time, causing its acceleration to also change. This can be seen in objects moving in a curved path or in objects experiencing varying levels of resistance or friction.

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