Lesson 2: Forces in Two Dimensions

In the scenario of a box sliding on a rough plane, what is the direction of the kinetic friction force?

• Opposite to the direction of motion

• Perpendicular to the support

• Vertically downwards

• Horizontally forwards

Given the FBD, which of the following must be true?

• The frictional force must be accelerating the system to the left.

• The box must be accelerating to the right.

• The box must be moving to the right.

• The FBD is incorrectly drawn. This situation isn't possible

A 80 kg skydiver is free falling at a constant velocity of 19 m/s. What is the net (total) force acting on her?

• 1,520 N
• 0 N
• 4.21 N
• Not enough information to answer

A car travels up a hill at constant speed. Which of the following diagrams best represents the forces acting on the car at this instant?

• 
• 
• 
• 

When resolving a force into its components, what does the horizontal component represent?

• Perpendicular to the x-axis
• Parallel to the x-axis
• Opposite to the x-axis
• Diagonal to the x-axis

What is the relationship between the normal force and the weight of an object on a flat surface?

• They are equal in magnitude and opposite in direction.

• They are perpendicular to each other.

• The normal force is always greater than the weight.

• The weight is always greater than the normal force.

What is the purpose of drawing a free body diagram (FBD) in physics?

• To visualize all the forces acting on an object.

• To calculate the velocity of an object.

• To determine the color of an object.

• To measure the temperature of an object.

• Fx= 235 N

  Fy= 152.4 N

• Fy= 235 N

  Fx= 152.4 N

• Fx= 514 N

  Fy= 333 N

In order to find the net force acting on the blue box in this example, which force needs to be resolved into its x and y components before we start our calculations?

• Friction

• Weight (Fg)

• Normal reaction

• None

Which of the following is the best expression for the Normal Force?

• F_N = mg cos(ϴ)

• F_N = mg sin(ϴ)

• F_N = mg sin(180-ϴ)

• F_N = mg cos(90-ϴ)