A question answer community on a mission

to share Solutions for all STEM major Problems.

to share Solutions for all STEM major Problems.

Cant find a problem on ToughSTEM?

0

Two blocks of ice, one four times as heavy as the other, are at rest on a frozen lake. A person pushes each block the same distance d. Ignore friction and assume that an equal force F is exerted on each block. Which of the following statements is true about the kinetic energy of the heavier block after the push?

It is smaller than the kinetic energy of the lighter block.

It is equal to the kinetic energy of the lighter block.

It is larger than the kinetic energy of the lighter block.

It cannot be determined without knowing the force and the mass of each block.

Added Thu, 30 Jul '15

Community

1

Add a Comment

Solutions

0

Let's do a comparison with some example values and then I'll explain the theory. Let's say that the first block is 10kg and the second block is 40kg (4 times heavier). Say that the force is 100N. Since F = ma, we know that:

For the first block:

F = ma

100N = 10kg * a

a1 = 10m/s2

For the second block:

F = ma

100N = 40kg * a

a2 = 2.5m/s2

Now say that the distance is 10m. We can find the final velocity of each block via:

Vf2 = V02 + 2a(d)

This is just one of the kinematic equations that you should know from previous chapters. So the final velocities are (assume each block starts from zero):

Block 1 = 14.14m/s

Block 2 = 7.07m/s

There is a pattern here, I'll explain at the end if you don't see it already.

Now that we have the final velocities, we can solve for the kinetic energy of each block, using the equation KE = 1/2mv2:

Block 1:

KE = 1/2mv2

KE = 1/2(10)(14.14)2

KE = 1,000J

Block 2:

KE = 1/2mv2

KE = 1/2(40)(7.07)2

KE = 1,000J

So the answer is B. It is equal to the kinetic energy of the lighter block.

Added Thu, 30 Jul '15

Community

1

Add a Comment

Add Your Solution!

Close

Click here to

Choose An Image

or

Get image from URL

GO

Close

Back

Add Image

Close

What URL would you like to link?

GO

α

β

γ

δ

ϵ

ε

η

ϑ

λ

μ

π

ρ

σ

τ

φ

ψ

ω

Γ

Δ

Θ

Λ

Π

Σ

Φ

Ω

∫

∮

∞

∝

∇

∴

→

↔

⊆

⊂

∀

∃

∈

∉

∪

∩

∅

Copied to Clipboard

Sign Up

to interact with the community. (That's part of how we ensure only good content gets on ToughSTEM)

OR

OR

ToughSTEM is completely free, and its staying that way. Students pay way too much already.

Almost done!

Please **check your email** to finish creating your account!

Welcome to the Club!

Choose a new Display Name

Only letters, numbers, spaces, dashes, and underscores, are allowed. Can not be blank.

Great! You're all set, .

A question answer community on a mission

to share Solutions for all STEM major Problems.

to share Solutions for all STEM major Problems.

Why

The Purpose

The Purpose

How

The Community

The Community

Give Feedback

Tell us suggestions, ideas, and any bugs you find. Help make ToughSTEM even better.