Problem 32
Question
You have just landed on Planet X. You release a 100-g ball from rest from a height of 10.0 m and measure that it takes 3.40 s to reach the ground. Ignore any force on the ball from the atmosphere of the planet. How much does the 100-g ball weigh on the surface of Planet X?
Step-by-Step Solution
Verified Answer
The ball weighs 0.173 N on Planet X.
1Step 1: Identify Known Values
We are given the initial height of the ball as 10 m, the time it takes to fall as 3.4 s, and the mass of the ball as 100 g (or 0.1 kg). We need to find the weight of the ball, which depends on the gravitational acceleration on Planet X.
2Step 2: Use the Kinematic Equation
To find the gravitational acceleration, use the kinematic equation: \[ h = \frac{1}{2} g t^2 \]Here, \( h = 10 \text{ m} \) and \( t = 3.4 \text{ s} \). Substitute these values into the equation to solve for \( g \).
3Step 3: Solve for Gravitational Acceleration
Rearrange the equation to solve for \( g \):\[ g = \frac{2h}{t^2} \]Substitute the known values: \[ g = \frac{2 \times 10}{(3.4)^2} \approx \frac{20}{11.56} \approx 1.73 \text{ m/s}^2 \]
4Step 4: Calculate the Weight of the Ball
The weight of the ball \( W \) is given by \( W = mg \), where \( m = 0.1 \text{ kg} \) and \( g = 1.73 \text{ m/s}^2 \).Substitute these values into the equation:\[ W = 0.1 \times 1.73 = 0.173 \text{ N} \]
Key Concepts
Kinematic EquationsWeight CalculationPlanetary Physics
Kinematic Equations
Kinematic equations are powerful tools in physics, especially when analyzing motion without regard to the causes of the motion. These equations relate variables like displacement, velocity, acceleration, and time, which can help us solve problems involving projectile motion, free fall, and much more.
In the context of our original exercise on Planet X, the kinematic equation helps us determine how fast things accelerate due to gravity.
When an object falls under gravity from rest, the equation \( h = \frac{1}{2} g t^2 \) comes in handy to find gravitational acceleration, denoted as \( g \). Here, \( h \) is the height from which the object falls, \( t \) is the time taken, and \( g \) is the gravitational acceleration.
To effectively use these equations:
This equation's simplicity is what makes it so useful in both classroom exercises and real-world physics problems!
In the context of our original exercise on Planet X, the kinematic equation helps us determine how fast things accelerate due to gravity.
When an object falls under gravity from rest, the equation \( h = \frac{1}{2} g t^2 \) comes in handy to find gravitational acceleration, denoted as \( g \). Here, \( h \) is the height from which the object falls, \( t \) is the time taken, and \( g \) is the gravitational acceleration.
To effectively use these equations:
- Identify the known variables.
- Plug them into the equation.
- Solve for the unknown.
This equation's simplicity is what makes it so useful in both classroom exercises and real-world physics problems!
Weight Calculation
Understanding weight calculation is crucial, as weight is often confused with mass.
While mass is the amount of matter in an object, weight is the force with which it is pulled towards a celestial body, like a planet.
Thus, weight depends on both the mass of the object and the gravity of the place it resides.
Mathematically, weight \( W \) is found using the equation:\[ W = mg \]where \( m \) is the mass in kilograms and \( g \) is the gravitational acceleration in \( \text{m/s}^2 \).
For example, on Earth, \( g \approx 9.8 \text{ m/s}^2 \), but on Planet X, we found \( g \approx 1.73 \text{ m/s}^2 \).
Once \( g \) is known, you simply multiply it by the mass to get the weight.
Since weight is a force, its unit is the Newton (N).
This calculation is critical for understanding how different planetary environments affect how heavy or light objects feel. Always remember, even if the mass does not change, the weight can vary greatly from planet to planet!
While mass is the amount of matter in an object, weight is the force with which it is pulled towards a celestial body, like a planet.
Thus, weight depends on both the mass of the object and the gravity of the place it resides.
Mathematically, weight \( W \) is found using the equation:\[ W = mg \]where \( m \) is the mass in kilograms and \( g \) is the gravitational acceleration in \( \text{m/s}^2 \).
For example, on Earth, \( g \approx 9.8 \text{ m/s}^2 \), but on Planet X, we found \( g \approx 1.73 \text{ m/s}^2 \).
Once \( g \) is known, you simply multiply it by the mass to get the weight.
Since weight is a force, its unit is the Newton (N).
This calculation is critical for understanding how different planetary environments affect how heavy or light objects feel. Always remember, even if the mass does not change, the weight can vary greatly from planet to planet!
Planetary Physics
Planetary physics is a fascinating field that explores the physical characteristics and phenomena of planets and other celestial bodies.
It encompasses the study of gravity, atmospheres, magnetic fields, and more.
For instance, the exercise on Planet X illustrates how gravitational acceleration differs from one planet to another.
These differences arise mainly due to the mass and radius of the planet.
Gravitational acceleration \( g \) is influenced by the planet’s mass \( M \) and the distance from its center \( r \), according to the formula:\[ g = \frac{GM}{r^2} \]where \( G \) is the universal gravitational constant.
Understanding such concepts can help us predict and explore how conditions vary across planets:
It encompasses the study of gravity, atmospheres, magnetic fields, and more.
For instance, the exercise on Planet X illustrates how gravitational acceleration differs from one planet to another.
These differences arise mainly due to the mass and radius of the planet.
Gravitational acceleration \( g \) is influenced by the planet’s mass \( M \) and the distance from its center \( r \), according to the formula:\[ g = \frac{GM}{r^2} \]where \( G \) is the universal gravitational constant.
Understanding such concepts can help us predict and explore how conditions vary across planets:
- How much does a space probe weigh on different planets?
- Would a human feel lighter or heavier?
- What would be the flight path of a projectile?
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