Friction Physics

Which of the following is the formula for calculating the frictional force when the normal force and the coefficient of friction are known?

Tags

DOK Level 1: Recall

• 19.6 N

• 9.8 N

• 2.0 N

• 0.4 N

Tags

DOK Level 2: Skill/Concept

Which of the following statements is true about static and kinetic friction?

• Static friction is always less than kinetic friction.

• Kinetic friction is always greater than static friction.

• Static friction can vary up to a maximum value, while kinetic friction is constant.

• Both static and kinetic friction are independent of the nature of surfaces in contact.

Tags

DOK Level 2: Skill/Concept

• 49 N

• 98 N

• 5 N

• 50 N

Tags

DOK Level 2: Skill/Concept

A person is pushing a box with known mass (m) to the right with a known force (F1). Another person is pushing the box to the left with known force (F2). There is friction between the box and floor with a known coefficient (μ) and the box moves to the right. Which of the following equations is correct to figure out the acceleration of the box?

• (F₁ + (-F₂) + (-μN)/m=a

• (F₁ + (-F₂) + μN)=a

• (F₁ + (-F₂))/m=a

• (F₁ + F₂ + μN)/m=a

Tags

NGSS.MS-PS2-2

What is static friction?

• The friction that acts on moving objects.

• The friction between two objects that are not moving relative to each other.

• The friction that only acts when an object is sliding.

• The friction that decreases as the speed of an object increases.

Frictional force depends on ____

• surface area in contact

• roughness of surface

• both a and b

• none of the above

Teddy Bear just ate a good meal and now weighs 40 kg. He attempts to run down the hall but slips and falls because the kinetic friction coefficient between his paws and the tile floor is .05. What is his normal force?

• 2 N

• 19.6 N

• 392 N

• 800 N

Tags

NGSS.MS-PS2-2

5kg box is pushed with 10 N of force. Static Friction coefficient is 0.3. Kinetic friction coefficient is .2. How fast does the box accelerate?

• 0 m/s²

• .18 m/s²

• 0.53 m/s²

• 1.2 m/s²

Tags

NGSS.MS-PS2-2

Whenever an object is moving, there is always this force opposing the motion:

• inertia

• momentum

• friction

• applied force