Vectors & friction review quiz

A car drives 40 km due east and then 50 km due west. What is the car’s overall displacement?

• 90 km east

• 10 km west

• 200 km north

• 1.2 km south

Which of the following equations represent the Pythagorean theorem?

• a² + b² + c²

• a² + b²= c²

• a² = b² + c²

• b² = a² + c²

You walk 20m south and then 20m east. Find the magnitude and direction of the resultant displacement.

• 40.2 m south east

• 37.4 m south west

• 28.3 m south east

• 16.5 m south west

The diagram above shows a triangle where r is not equal to 90°. Omar has been given the values of some lengths and angles. The cosine law R² = A² + B²+ 2AB Cos theta may be used when a question involves:

• One angle and two lengths

• Two angles and two lengths

• Three angles and one length

• Three angles and three lengths

Friction is caused by two objects rubbing. This is due to:

• The high points on each object come in to contact and temporarily bond.

• The high points on each object cause heat which results in a change in speed.

• The high points on each object cause heat which results in a change in speed.

• The low points get trapped while objects move

Complete the statement: “Friction forces are always ____________”

• Parallel to the normal force

• Greater than the normal force

• Equal to the normal force

• Perpendicular to the normal force

Khalifa pushes a box of toys across a wooden floor. The box of toys weighs 150 N. The coefficient of static friction between the floor and the box is 0.40. How hard must Khalifa push to start moving the box?

• 60 N

• 150.4 N

• 375 N

• 149.6 N

A 1.6 kg block slides freely across a rough surface such that the block slows down with an acceleration of —1.5 m/s². What is the coefficient of kinetic friction between the block and the surface?

• 0.51

• 0.11

• 0.15

• 0.55

The size of a friction force is dependent on which of the following?

• The speed at which two objects rub

• The surface area that comes into contact when two objects

  rub

• The volume of the two objects rubbing

• The normal force between the two objects rubbing

What is the term used to describe a force that equals the sum of two or more forces?

• Resultant

• Equilibrant

• Normal

• Tension