Cast Science Test Practice

Lesson 26 Question 1

Lead and cast iron have a coefficient of static friction of 0.43. Based on the results in Table 2, if Figure 1 included the results of the same experiment performed using lead and cast iron, the line formed from the results of the experiment would most likely fall:

• above tire/asphalt

• between brick/wood and tire/asphalt

• between tire/asphalt and tire/grass

• below tire/grass

Tags

NGSS.MS-PS2-2

Lesson 26 Question 2

For situations in which the normal forces between surfaces are equal, materials that have a lower coefficient of friction will experience smaller frictional forces between one another compared to materials with a higher coefficient of friction. Based on this information and the results of the experiment presented in Figure 2, which unknown material will experience the smallest frictional force?

• Unknown 1

• Unknown 2

• Unknown 3

• Unknown 4

Suppose further research shows that the use of a particular lubricant allows materials to begin sliding relative to one another with only half the frictional force required without any lubrication. How would the researchers explain this result? The researchers would most likely argue that using the lubricant:

• decreases the coefficient of friction between the materials, decreasing the frictional force between them

• decreases the normal force between the materials, decreasing the frictional force between them

• increases the coefficient of friction between the materials, increasing the frictional force between them

• increases the normal force between the materials, increasing the frictional force between them

Tags

NGSS.HS-PS2-1

Lesson 26 Question 4

Suppose research had been conducted to find the coefficient of friction between another set of materials, horseshoes and rubber. Based on Tables 1 and 2, if the frictional force between the horseshoe and rubber is 32.8 N when the normal force between them is 49 N, and the frictional force is 95 N when the normal force between them is 147 N, the coefficient of friction between the horseshoe and rubber is most likely:

• greater than 0.72

• between 0.72 and 0.60

• between 0.60 and 0.35

• less than 0.35

Lesson 26 Question 5

When chromium is in contact with itself, it has a coefficient of friction about three times as large as the coefficient of friction between carbon and steel. Given this information, the frictional force that two pieces of chromium would feel when they are in contact with one another with a 50 N normal force between them would be approximately:

• 21 N

• 14 N

• 7 N

• 2 N

Tags

NGSS.MS-PS2-2

Lesson 27 Question 1

Suppose studies suggest that the frictional force between two objects drops as they begin to slide. How would scientist 2 explain this result? Scientist 2 would most likely argue that:

• as the object begins to slide, the coefficient of kinetic friction takes over, which is lower than the coefficient of static friction

• as the object begins to slide, the normal force between the object and surface decreases

• as the object begins to slide, the coefficient of kinetic friction takes over, which is higher than the coefficient of static friction

• as the object begins to slide, the normal force between the object and the surface increases

Tags

NGSS.MS-PS2-2

Lesson 27 Question 2

Suppose the experiment is performed again for steel in contact with glass, and it is determined that for a situation in which the objects experience a 5N normal force, a frictional force of 4N is measured just before the objects begin to slide. Based on Equation 2, the coefficient of static friction between steel and glass is most likely to be:

• less than 0.5

• between 0.5 and 0.7

• between 0.7 and 0.9

• greater than 0.9

Lesson 27 Question 3

Scientists are able to determine that the coefficient of static friction between wood and concrete is 3 times higher than friction between a wet road and tire. Given this information, as well as scientist 2's viewpoint ,the coefficient of static friction between wood and concrete is approximately:

• 0.2

• 0.4

• 0.6

• 0.8

Lesson 27 Question 4

When two diamond are rubbed together, the frictional force just before they begin to slide is about one tenth the normal force between them, and once they begin sliding, the frictional force drops to about half that. Based on Equation 2, which of the following are the most likely coefficients of friction for diamond-diamond contact?

• ϥ_S = 0.6 ϥ_K = 0.3

• ϥ_S = 0.5 ϥ_K = 0.25

• ϥ_S = 0.25 ϥ_K = 0.125

• ϥ_S = 0.1 ϥ_K = 0.05

Tags

NGSS.MS-PS2-2

Suppose the experiment is run twice, once using a combination of wood against wood and again using a combination of wood against ice. The normal and frictional forces for each combination are given in the table.

Based on Equation2 and Scientist 2's statement, which combination of materials has the lowest coefficient of static friction?

• Wood/wood because it has the smallest ratio of frictional force to normal force

• Wood/wood because it has the smallest ratio of normal force to frictional force

• Wood/ice because it has the smallest ratio of frictional force to normal force

• Wood/ice because it has the smallest ratio of normal force to frictional force