Question

Suppose you drop an object and it strikes the ground. you can calculate the velocity of the object as it strikes the ground using the law of conservation of energy. in order to do this, you need to know the original height of the object. do you also need to know the mass of the object? why or why not?

a. you do not need to know the mass because you can compute it based on the provided information.
b. you do not need to know the mass because it cancels out.
c. you need to know the mass of the object in order to compute the kinetic and gravitational potential energies.
d. you need to know the mass of the object in order to compute the elastic potential energy.

Answer 1

Answer: B you do not need to know the mass because it cancels out

Step-by-step explanation:

Answer 2

b)

Step-by-step explanation:

• Assuming no friction forces present, the total mechanical energy must be conserved, so at any moment, the sum of the gravitational potential energy and the kinetic energy must be the same.
• When the object is dropped, all the energy is gravitational, as follows:
• E = m*g*h (1)
• When the object strikes the ground, if we choose the ground as the zero reference level for the gravitational potential energy, all the energy is kinetic:
• E = 1/2*m*v² (2)
• Since E is constant, left sides in (1) and (2) are equal each other, so the right sides must be equal each other too.
• Since the mass is present in the right side of (1) and (2) it cancels out, so b) is the right answer.