Projectile motion with mass height and range

In summary: The mass of the boulder will cancel out in the equations, so it doesn't matter what it is. In summary, the conversation is about a homework question involving a boulder rolling off a cliff and whether conservation of energy or constant acceleration equations should be used to solve it. The person asking the question is wondering if the mass of the boulder is necessary for the solution. The experts suggest using the constant acceleration equations and state that the mass of the boulder will not affect the outcome.
  • #1
SPiazzo
7
0
Hello all I have a question I was hoping someone could answer for my homework.
A 78.0-kg boulder is rolling horizontally at the top of a vertical cliff that is h1 = 16 m above the surface of a lake, as shown in the figure below. The top of the vertical face of a dam is located d = 110 m from the foot of the cliff, with the top of the dam level with the surface of the water in the lake. A level plain is h2 = 28 m below the top of the dam.
a) What must be the minimum speed of the rock just as it leaves the cliff so it will travel to the plain without striking the dam?
b) How far from the foot of the dam does the rock hit the plain?

from what I could find on Google about it, it seems to be a conservation of energy problem as that is the only way you can relate mass to anything. As all of the kinematic equations I have seen in my book and notes have no variable for mass. I am also fairly certain that the limited amount of information in the problem means that the mass is simply not there for no reason.
Any help you could give would be great! Thanks!
 
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  • #2
Welcome to PF!

Hello SPiazzo! Welcome to PF! :smile:
SPiazzo said:
from what I could find on Google about it, it seems to be a conservation of energy problem as that is the only way you can relate mass to anything.

No, just use the standard constant acceleration equations. :wink:
 
  • #3
Please post homework questions in our homework section - I moved your thread.

I agree with tiny-tim, just use the formulas for constant acceleration.
 

FAQ: Projectile motion with mass height and range

1. How does mass affect projectile motion?

The mass of a projectile has no effect on its trajectory or range, as long as air resistance is negligible. This is because the only force acting on a projectile is gravity, which is independent of mass.

2. Does height affect the range of a projectile?

Yes, the height from which a projectile is launched can affect its range. The higher the launch position, the longer the projectile will stay in the air and the farther it will travel horizontally. This is due to the initial vertical velocity imparted to the projectile, which will cause it to stay in the air for a longer period of time.

3. What factors affect the range of a projectile?

The range of a projectile is affected by the initial velocity, launch angle, and air resistance. A higher initial velocity and launch angle will result in a longer range, while air resistance will decrease the range.

4. Can a projectile have negative range?

Yes, a projectile can have negative range if it is launched at a high enough angle and with enough initial velocity. This means that the projectile will land behind the point of launch, in the opposite direction of its initial motion.

5. How is projectile motion with mass, height, and range calculated?

The equations used to calculate projectile motion with mass, height, and range are derived from the laws of motion and gravity. The equations take into account the initial velocity, launch angle, and air resistance to determine the trajectory, time of flight, and range of the projectile.

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