Find the gravitational field strength of planet X

In summary, the formula for weight/mass is gravitational field strength, which can be calculated by dividing the change in velocity by the change in time on a straight line portion of the velocity vs. time graph.
  • #1
ellieee
78
6
Homework Statement
find gravitational field strength of planet X
Relevant Equations
weight/mass = gravitational field strength.
weight/mass = gravitational field strength.
my working is ->
weight = 150kgx10m/s² = 1500N
mass = 150kg
gravitational field strength= 10N/kg.
is this correct?
 

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  • #2
Not clear what the question is, but the answer is not correct.
How did you determine the weight ?

##\ ##
 
  • #3
You need to calculate the acceleration in free fall from the graph that was provided. This will give you the ## g ## in the formula ## W=mg ##. In any case, your answer is incorrect.
 
  • #4
Charles Link said:
You need to calculate the acceleration in free fall from the graph that was provided. This will give you the ## g ## in the formula ## W=mg ##. In any case, your answer is incorrect.
do I calculate it using the part of the graph where the rocket is experiencing negative velocity ?
 
  • #5
The graph is a graph of velocity vs. time. The acceleration will be negative and is the same anywhere on the straight line segment after the rocket has burnt out, even when the velocity is negative.
 
  • #6
hm so how do I calculate the acceleration from the graph then ?
 
  • #7
Pick two points on the line segment: acceleration ## a=\frac{v_2-v_1}{t_2-t_1} ##.
 
  • #8
a
Charles Link said:
Pick two points on the line segment: acceleration ## a=\frac{v_2-v_1}{t_2-t_1} ##.
any 2 points ? but the acceleration is not constant throughout though?
 
  • #9
On a straight line portion (of the velocity vs. time graph) the acceleration is constant. It is positive on the ascending straight line segment, where the fuel is propelling the rocket, and then it goes negative, and stays constant in the entire descending straight line segment. (By descending, I'm referring to the change in velocity. The slope of the segment of velocity vs. time is downward, even when the velocity is still positive).
 
  • #10
Charles Link said:
On a straight line portion (of the velocity vs. time graph) the acceleration is constant. It is positive on the ascending straight line segment, where the fuel is propelling the rocket, and then it goes negative, and stays constant in the entire descending straight line segment. (By descending, I'm referring to the change in velocity. The slope of the segment of velocity vs. time is downward, even when the velocity is still positive).
so I pick any 2 points from 20-90s?
 
  • #11
Yes, go ahead and compute it. If you are skeptical that you will get the same answer, try 2 pairs of points.

Note: This is basically an exercise in algebra. You may not remember it, but the slope on a straight line is ## m=\frac{y_2-y_1}{x_2-x_1} ##.
 
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FAQ: Find the gravitational field strength of planet X

1. What is the formula for calculating the gravitational field strength of a planet?

The formula for calculating the gravitational field strength of a planet is F = GmM/r^2, where F is the gravitational force, G is the universal gravitational constant, m and M are the masses of the two objects, and r is the distance between them.

2. How is the gravitational field strength of a planet related to its mass and radius?

The gravitational field strength of a planet is directly proportional to its mass and inversely proportional to the square of its radius. This means that as the mass of a planet increases, its gravitational field strength increases, and as its radius increases, its gravitational field strength decreases.

3. Can the gravitational field strength of a planet be negative?

No, the gravitational field strength of a planet cannot be negative. It is always a positive value, as gravity is always an attractive force.

4. How does the gravitational field strength of a planet affect objects on its surface?

The gravitational field strength of a planet determines the strength of the gravitational force exerted on objects on its surface. The higher the gravitational field strength, the stronger the force of gravity, and the more weight an object will have on the planet's surface.

5. How do scientists measure the gravitational field strength of a planet?

Scientists can measure the gravitational field strength of a planet by using the formula F = GmM/r^2 and plugging in known values for the mass and radius of the planet. They can also use tools such as gravimeters, which measure the gravitational pull of the planet at different locations, to calculate the average gravitational field strength.

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