Work done by friction on a hockey puck

[I_Try_Math]

Homework Statement

A hockey puck of mass 0.17 kg is shot across a rough floor with the roughness different at different places, which can be described by a position-dependent coefficient of kinetic friction. For a puck moving along the x-axis, the coefficient of kinetic friction is the following function of x, where x is in m: u(x) = 0.1 + 0.05x. Find the work done by the kinetic frictional force on the hockey puck when it has moved from x = 0 to x = 2

Relevant Equations

[math]W = \int_0^2 F(x) \, dx[/math]

The answer key claims the answer is -0.9 J.

By my math it should be -0.501 J, is that incorrect?

 

[erobz]

Homework Statement: A hockey puck of mass 0.17 kg is shot across a rough floor with the roughness different at different places, which can be described by a position-dependent coefficient of kinetic friction. For a puck moving along the x-axis, the coefficient of kinetic friction is the following function of x, where x is in m: u(x) = 0.1 + 0.05x. Find the work done by the kinetic frictional force on the hockey puck when it has moved from x = 0 to x = 2
Relevant Equations: \(\displaystyle W = \int_0^2 F(x) \, dx\)

The answer key claims the answer is -0.9 J.

By my math it should be -0.501 J, is that incorrect?
View attachment 339633

You mean " by Wolfram Alpha's math" its ##-0.501 \rm{J}##. Wolframs math looks correct to me also...

 

[I_Try_Math]

You mean " by Wolfram Alpha's math" its ##-0.501 \rm{J}##. Wolframs math looks correct to me also...

Thanks, it's frustrating trying to learn when you can't check your work against the answer key.

 

[Delta2]

I assume the "0.17kg" was a typo.

0.17x9.8=1.67!?!!

But yeah I got no clue how heavy is a hockey ball, hockey isn't popular here in Greece.

 

[jbriggs444]

0.17x9.8=1.67!?!!

But yeah I got no clue how heavy is a hockey ball, hockey isn't popular here in Greece.

I had to look it up. Google "how heavy is a hockey puck".

Ice hockey requires a hard disk of vulcanized rubber. A standard ice hockey puck is black, 1 inch (25 mm) thick, 3 inches (76 mm) in diameter, and weighs between 5.5 and 6 ounces (156 and 170 g);[6] some pucks are heavier or lighter than standard (see below). Pucks are often marked with silkscreened team or league logos on one or both faces.[6] Pucks are frozen before the game to reduce bouncing during play.[6]