Solving for Acceleration when weight is in Newtons instead of Kg

In summary, the astronaut and equipment weigh 1,960 N on Earth and are weightless in space. With 100 N thrust from a rocket pack firing for 2.0s, the resulting final velocity can be calculated by first finding the acceleration, which can be obtained by dividing the weight by the acceleration due to gravity. Then, the final velocity can be calculated using the formula vf = a * t - vi. Weight is a force measured in Newtons, while mass is measured in kg.
  • #1
tommyboy2
6
0

Homework Statement



On the earth, an astronaut and the equipment weigh 1,960 N. Weightless in space, the motionless astronaut and equipment are accelerated by rocket pack with
100 N thrust, that fires for 2.0s. What is the resulting final velocity? (Hint: First calculate the acceleration. Also take the initial velocity as zero)

Homework Equations



I am not sure how to solve for the Acceleration when mass is in Newtons and not Kg. I can not use the formula which I think i use which is f=ma. then the final velocity = acceleration * time - initial velocity

The Attempt at a Solution



I divided 1960 N by 9.8 m/s^2= 200kg <<If that is right please explain because I don't understand.

200kg * a = 100N which equals a=0.5m/s^2

Vf = 0.5m/s^2 * 2sec - 0 = 1m/sec for the final velocity.
 
Physics news on Phys.org
  • #2
Weight is a force, measured in Newtons. Mass is, well, mass, measured in kg. You must get the distinction clear.
 
  • #3
i know but the problem has given me a weight of the astronaut and his equipment in Newtons not in kg so how can i solve for the acceleration
 
  • #4
tms is pointing out the misuse here: "when mass is in Newtons and not Kg".
You are told the weight at Earth's surface in N, not the mass. From that you correctly deduced the mass.
 
  • #5
I think i got it now. But one more question, so is that always how you would change the Newtons into a mass in kg by dividing it by the acceleration due to gravity or is there a formula to manipulate.
 
  • #6
tommyboy2 said:
is that always how you would change the Newtons into a mass in kg by dividing it by the acceleration due to gravity
Yes. Weight is only meaningful in a specified context (i.e. the local gravitational field) and is given by mass * field strength. So given the weight you can divide by the field strength to get the mass.
 
  • #7
okay well thanks guys the rest should be right then.
 

1. How do you convert Newtons to kilograms?

To convert Newtons to kilograms, you can use the formula: 1 Newton = 0.102 kg. This means that you divide the weight in Newtons by 9.8 (the acceleration due to gravity) to get the weight in kilograms.

2. Why is it important to know the weight in Newtons when solving for acceleration?

Knowing the weight in Newtons is important because it allows you to accurately calculate the force of gravity acting on an object. This force is necessary to calculate the acceleration of the object using Newton's second law of motion (F=ma).

3. Can acceleration be negative when weight is in Newtons?

Yes, acceleration can be negative when weight is in Newtons. This indicates that the object is slowing down or moving in the opposite direction of the applied force.

4. How does air resistance affect the weight in Newtons and the acceleration of an object?

Air resistance does not affect the weight in Newtons, as weight is a measure of the force of gravity acting on an object. However, air resistance can affect the acceleration of an object by opposing the motion and causing a decrease in acceleration.

5. Is there a difference in solving for acceleration when weight is in Newtons compared to when it is in kilograms?

There is no difference in solving for acceleration when weight is in Newtons compared to kilograms. The only difference is in the units used in the calculation. Both methods will give you the same result for acceleration.

Similar threads

  • Introductory Physics Homework Help
2
Replies
42
Views
3K
  • Introductory Physics Homework Help
Replies
3
Views
705
  • Introductory Physics Homework Help
Replies
5
Views
315
  • Introductory Physics Homework Help
Replies
6
Views
869
  • Introductory Physics Homework Help
Replies
5
Views
3K
  • Introductory Physics Homework Help
Replies
9
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
323
  • Introductory Physics Homework Help
Replies
22
Views
2K
  • Introductory Physics Homework Help
3
Replies
97
Views
3K
  • Introductory Physics Homework Help
Replies
20
Views
1K
Back
Top