Engineering Physics 5.3 Formative

The force that opposes the motion of one surface over another.

T or F: The force that accelerates you forward when you start walking is friction.

• True

• False

Tags

NGSS.HS-PS2-1

Match the following descriptions to the type of friction

• Static friction

• Opposes motion on objects that aren't moving

• Rolling friction

• Opposes motion in a liquid or gas

• Fluid friction

• Opposes motion on objects that are sliding over a surface

• Kinetic friction

• Opposes motion on objects that are on wheels

Which of the following are true of kinetic friction?

• it opposes the motion of the surfaces

• it is proportional to the normal force between the surfaces

• it is the same regardless of the speed of the surfaces

• it is the same regardless of the area of contact between the surfaces

Match the coefficients of kinetic friction with the materials.

• 0.40

• waxed ski on snow

• 0.57

• steel on ice

• 0.003

• human joints

• 0.05

• wood on leather

• 0.06

• steel on glass

The equation used to calculate the force of kinetic friction is
​ (a)   =​ (b)   x​ (c)  

• force of kinetic friction
• coefficient of friction
• normal force

The equation used to calculate the maximum force of static friction is
​ (a)   =​ (b)   x​ (c)  

• maximum force of static friction
• coefficient of static friction
• normal force

Practice Problem 32: A baseball player slides into third base with an initial speed of 4.0 m/s. If the coefficient of friction between the player and the ground is 0.46, how far does he slide before coming to a rest (round to one decimal place)?

Tags

NGSS.HS-PS2-1

Practice Problem 34: Part A-When you push a 1.80-kg book that is resting on a tabletop, a force of 2.25 N is required to start the book sliding. Once it is sliding, however, a force of only 1.50 N keeps the book moving with constant speed. What is the coefficient of static friction between the book and the tabletop?
(round to three decimal places)

Tags

NGSS.HS-PS2-1

Practice Problem 34: Part B-When you push a 1.80-kg book that is resting on a tabletop, a force of 2.25 N is required to start the book sliding. Once it is sliding, however, a force of only 1.50 N keeps the book moving with constant speed. What is the coefficient of kinetic friction between the book and the tabletop?
(round to three decimal places)