Newtons Law / Kinematic problem?

In summary, the conversation involves a question about finding the angle between a frictionless ramp and the horizontal, using kinematics and Newton's laws. One person's attempt resulted in an angle of 9.6 degrees, while another person's method led to an angle of 12.275 degrees, which was later corrected due to a small arithmetic error. It is suggested to approach the problem as a conservation of energy problem, but the person mentions that they have not covered energy in their class yet.
  • #1
physstudent1
270
1
Hello, the question I'm having trouble with is:

"A 8.00kg block of ice, released from rest at the top of a 1.5 m long frictionless ramp, slides downhill, reaching a speed of 2.5 m/s at the bottom.
What is the angle between the ramp and the horizontal?"

My first attempt to solve this problem was that I would use kinematics to get the acceleration. And then use the acceleration and Newton's laws to find the angle. By using kinematics I got the equation 2.5^2 = 0 + 2(a)(1.5)
I then got a to be 1.64. Using that I set the equation 8gsin(theta) = 1.64(8). Eventually getting theta to equal 9.6 degrees. But when I compared my answer to the a fellow classmate He got 12.275, but I can't really follow his work and there's no answer in the back of the book, so can anyone help?
 
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  • #2
Since there is no friction, it may be easier to consider this problem as a conservation of energy problem.
 
  • #3
We have not gotten to energy yet in my class :(. This is the third chapter all we have done is kinematics, projectile motion, and now this.
 
  • #4
I've just looked through your work and it appears it's just your arithmetic that's letting you down. Your kinematic equation is correct, but your value for acceleration is not; try solving for acceleration again.
 
  • #5
Ah jeez I'm so dumb thanks alot! I just have sloppy hand writting so I turned the 1.5 into a 1.9 which gave me the wrong answer thanks alot.
 

1. What is Newton's Law of Motion?

Newton's Law of Motion is a fundamental law in physics that describes the relationship between an object's mass, acceleration, and the applied force. It states that an object will remain at rest or in motion with a constant velocity unless acted upon by an external force.

2. What is the difference between Newton's First, Second, and Third Laws?

Newton's First Law, also known as the Law of Inertia, states that an object will remain at rest or in motion with a constant velocity unless acted upon by an external force. Newton's Second Law, also known as the Law of Acceleration, states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. Newton's Third Law, also known as the Law of Action and Reaction, states that for every action, there is an equal and opposite reaction.

3. How do you use Newton's Laws to solve kinematic problems?

To solve kinematic problems, you can use Newton's Second Law to find the net force acting on an object. Then, you can use this net force and the object's mass to calculate its acceleration. Using the equations of kinematics, you can then find the object's displacement, velocity, and time.

4. Can Newton's Laws be applied to all types of motion?

Yes, Newton's Laws can be applied to all types of motion, including linear, rotational, and projectile motion. These laws are fundamental principles that govern the behavior of objects in motion.

5. What are some real-life applications of Newton's Laws?

Newton's Laws have countless real-life applications, such as understanding the motion of planets and satellites, designing vehicles and aircraft, and predicting the behavior of objects in sports and games. They are also essential in engineering and technology, from building bridges to designing roller coasters.

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