Physics displacement velocity mass elastic/inelastic help

In summary: For a perfectly elastic collision, the kinetic energy before the collision is equal to the kinetic energy after the collision. So the equation would be 0.5m1v1^2 = 0.5m2v2^2. From this, we can solve for m2.
  • #1
Jphil
3
0
NO TEMPLATE BECAUSE THREAD WAS STARTED IN WRONG FORUM

A wrecking ball is a heavy steel ball, usually hung from a crane that is used for demolishing large buildings. Suppose we had a crane with a wrecking ball with a mass of m1 = 12,000 lbs. The crane produces a displacement on the ball of a height of Δy = 8.25 meters. As the crane stops turning, the wrecking ball swings downward in a circular motion. The operator of the crane was not paying any attention as he produced a displacement on the ball and at the bottom of the swing the ball collides with a parked vehicle that has a mass of m2.
a. At the bottom of the swing, what is the wrecking balls velocity?
b. Suppose when the wrecking ball swings down, its collision with the parked vehicle is perfectly elastic and the wrecking ball and the parked vehicle both experience the same velocity but in different directions. What is the mass m2 of the parked vehicle?
c. Assume the collision is perfectly inelastic and the wrecking ball and parked vehicle stay stuck together. What is the velocity of the two objects immediately after they collide?
d. Assuming with the same condition as in part (c.), what is the wrecking ball and parked vehicles new displacement Δy? (what is its maximum height hf of the two objects)
 
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  • #2
Jphil said:
a. At the bottom of the swing, what is the wrecking balls velocity?
b. Suppose when the wrecking ball swings down, its collision with the parked vehicle is perfectly elastic and the wrecking ball and the parked vehicle both experience the same velocity but in different directions. What is the mass m2 of the parked vehicle?
c. Assume the collision is perfectly inelastic and the wrecking ball and parked vehicle stay stuck together. What is the velocity of the two objects immediately after they collide?
d. Assuming with the same condition as in part (c.), what is the wrecking ball and parked vehicles new displacement Δy? (what is its maximum height hf of the two objects)

one can calculate the velocity of the ball by using energy conservation.i.e. the potential energy must have converted to kinetic energy.
for b...one can use conservation of momentum as well as energy as the collision is elastic.and calculate the mass
for c again you can use momentum conservation to get velocity and can calculate height.
 
  • #3
Jphil said:
NO TEMPLATE BECAUSE THREAD WAS STARTED IN WRONG FORUM

A wrecking ball is a heavy steel ball, usually hung from a crane that is used for demolishing large buildings. Suppose we had a crane with a wrecking ball with a mass of m1 = 12,000 lbs. The crane produces a displacement on the ball of a height of Δy = 8.25 meters. As the crane stops turning, the wrecking ball swings downward in a circular motion. The operator of the crane was not paying any attention as he produced a displacement on the ball and at the bottom of the swing the ball collides with a parked vehicle that has a mass of m2.
a. At the bottom of the swing, what is the wrecking balls velocity?
b. Suppose when the wrecking ball swings down, its collision with the parked vehicle is perfectly elastic and the wrecking ball and the parked vehicle both experience the same velocity but in different directions. What is the mass m2 of the parked vehicle?
c. Assume the collision is perfectly inelastic and the wrecking ball and parked vehicle stay stuck together. What is the velocity of the two objects immediately after they collide?
d. Assuming with the same condition as in part (c.), what is the wrecking ball and parked vehicles new displacement Δy? (what is its maximum height hf of the two objects)
I assume this was moved to a homework forum by a moderator. As a result, it is in a homework forum without including any attempt at a solution, which is against forum rules. @Jphil, please supply an attempt. At the very least, mention what physical principles and equations you consider relevant.
 
  • #4
i used mgh=0.5mv^2 for part a and got 12.7 m/s ^2 for the answer I am not sure if that was right . and then i was stuck for the rest of the attempts
 
  • #5
Jphil said:
i used mgh=0.5mv^2 for part a and got 12.7 m/s ^2 for the answer I am not sure if that was right . and then i was stuck for the rest of the attempts
I confirm your answer for part a.
For part b, what do you think the question means by "both experience the same velocity"?
What equations or principles do you know relating to elastic collisions?
 
  • #6
haruspex said:
I confirm your answer for part a.
For part b, what do you think the question means by "both experience the same velocity"?
What equations or principles do you know relating to elastic collisions?
i think that elastic collision most of the velocity becomes transferred to the object?
 
  • #7
Jphil said:
i think that elastic collision most of the velocity becomes transferred to the object?
No,perfectly elastic means there is no loss of mechanical energy. What equation does that give you?
 

1. What is the difference between displacement and distance in physics?

Displacement is a vector quantity that refers to the change in position of an object, taking into account the direction of the change. Distance, on the other hand, is a scalar quantity that refers to the total path length traveled by an object without considering direction.

2. How is velocity calculated in physics?

Velocity is calculated by dividing the change in displacement by the change in time. This is represented by the equation v = Δx/Δt, where v is velocity, Δx is change in displacement, and Δt is change in time.

3. What is the difference between mass and weight in physics?

Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity acting on an object. Mass is measured in kilograms (kg), while weight is measured in newtons (N).

4. What is elastic and inelastic collision in physics?

Elastic collision is a type of collision where the total kinetic energy of the system is conserved, meaning that the total energy before and after the collision remains the same. Inelastic collision, on the other hand, is a type of collision where some of the kinetic energy is lost, usually due to the deformation of objects involved in the collision.

5. How can I apply the principles of physics to solve problems involving displacement, velocity, mass, and elasticity?

To solve problems involving these concepts, it is important to first identify the known and unknown variables, and then use the appropriate equations and principles to solve for the unknown. Practice and understanding of the fundamental principles of physics is key to successfully solving these types of problems.

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