I don't know where to start with this one. "Find the work done accelerating a 2 kg box from 2m/s to 3 m/s." Can't find acceleration because I don't know time. In fact, I don't see how any of the kinematic equations can help me out to find either distance or acceleration so that I can then find Force and then work. What am I missing?

Question

I don't know where to start with this one. "Find the work done accelerating a 2 kg box from 2m/s to 3 m/s." Can't find acceleration because I don't know time. In fact, I don't see how any of the kinematic equations can help me out to find either distance or acceleration so that I can then find Force and then work. What am I missing?

Answer 1

You don't need to know the time or the acceleration. Just compute the increase in kinetic energy.

delta KE = work
= (1/2)*(2 kg)[3^2 - 2^2]

Answer 2

Thanks. Is this the only way to calculate because in our lesson we only learned the formula for work =fd? We've haven't done KE yet.

Answer 3

You could assume a uniform acceleration time, T. You would find that the force required would be inversely proportional to T, and the distance would be proportional, so that it would cancel out when calculating F*d.

Vav*T = (V2 + V1)/2 * T = d
F = M a = M * (V2 - V1)/T

F*d = (1/2) M (V2^2 - V1^2)

Answer 4

Thank you very much!

Answer 5

To find the work done in accelerating a 2 kg box from 2 m/s to 3 m/s, you need to use the concept of work-energy theorem. The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.

First, let's calculate the change in kinetic energy of the box. The formula for kinetic energy is:

Kinetic energy = 0.5 * mass * velocity^2

Initial kinetic energy = 0.5 * 2 kg * (2 m/s)^2 = 4 J
Final kinetic energy = 0.5 * 2 kg * (3 m/s)^2 = 9 J

Now, calculate the change in kinetic energy:

Change in kinetic energy = Final kinetic energy - Initial kinetic energy
= 9 J - 4 J
= 5 J

Since work done is equal to the change in kinetic energy, the work done in accelerating the box is 5 Joules (J).

To calculate the work done using force, you need to know the distance traveled. Without knowing the distance or the time, you cannot directly use force-distance or force-time relationships to find the work done. However, by using the work-energy theorem, you can find the work done using the change in kinetic energy.

So, in this case, you can find the work done by directly calculating the change in kinetic energy without needing to know the distance or the time.