Quiz

QUIZ

1. What statement is true of the concept of force?

a. It has a direction but no magnitude b. It has a magnitude but no direction c. It is a scalar quantity d. It has a magnitude and direction

Answer: d. Force is a vector in that it has a magnitude and a direction. It can be added to displacement, velocity, and acceleration as one of the vector quantities in nature.

2. What can be said of a standard force?

a. It is a force that applies to different force situations. b. It is a reproducible force. c. It does not apply to things such as magnetism. d. It is an external force applied to an object.

Answer: b. A standard force is a reproducible force that applies to a specific situation. A spring or rubber band will have a certain standard force called the restoring force and the forces seen in magnetism are also standard forces. These are not applied externally to an object.

3. In describing a Newton in relationship to the pound, what is the pound equivalent of one Newton?

a. 1.2 pounds b. 0.225 pounds c. 0.62 pounds d. 2.85 pounds

Answer: b. While the Newton or the pound can be used to define force, you need to know that one Newton is the equivalent of 0.225 pounds.

4. An object on earth has a mass of 2 kilograms. According to Newton’s second law, the weight of the object in Newtons is what?

a. 2 Newtons b. 9.8 Newtons c. 19.6 Newtons d. 24.8 Newtons

Answer: c. Weight is in Newtons and is related to the acceleration due to gravity, which is 9.8 meters per second squared. Because force equals mass times the acceleration due to gravity, the weight is 19.6 Newtons.

5. What is considered a force on earth that is acted upon at all times?

a. Thrust b. Weight c. External forces d. Internal forces

Answer: b. Weight is the only force of all of these that needs to be acted upon at all times. Even in orbital space, there is some gravitational force but it is far less than the weight observed on earth. Thrust and external forces do not necessarily get acted upon and internal forces, by definition, get opposed equally and oppositely within a system.

6. What is the force called that opposes the force of a load on a table?

a. Restoring force b. Loading force c. Reacting force d. Elastic force

Answer: a. The force on the load will be called the restoring force and is identical to the restoring force of a spring or trampoline. It isn’t noticed on most tables or other load-bearing surfaces because these are relatively firm surfaces; however, they do deform to a limited degree.

7. In solving the weight parallel to the incline of an object that is sitting on the incline which is itself at an angle theta to the ground, what is the parallel weight?

a. Mass times the force of gravity times the tangent of theta b. Mass times the cosine of angle theta c. Mass times the force of gravity times the cosine of angle theta d. Mass times the force of gravity times the sine of angle theta

Answer: d. The weight that is parallel to the incline of an object that is sitting on an incline at angle theta is equal to the mass times the force of gravity times the sine of the angle theta. Once you know the angle theta and the weight of the object, you can resolve the weight of the object with respect to the x-axis or parallel to the incline.

8. What is the perpendicular weight on an incline when the incline is at the angle theta?

a. Mass times the force of gravity times the tangent of theta b. Mass times the cosine of angle theta c. Mass times the force of gravity times the cosine of angle theta d. Mass times the force of gravity times the sine of angle theta

Answer: c. The perpendicular weight on an incline is equal to the object’s weight (the mass times the force of gravity) multiplied by the cosine of angle theta, where theta is the angle of the incline. This perpendicular weight is the opposite force to the normal force or normal weight of an object.

9. What is drag force?

a. It is the force associated with pulling an object along an incline b. It is the force that opposes the direction of an object traveling through air or a fluid c. It is the friction of wheels on a flat surface d. It has a magnitude and direction toward the direction of movement of an object that is being pushed by another object.

Answer: b. Drag force is the force that opposes the direction of an object traveling through air or fluid. It applies to forces in water for a swimmer or boat or to a dragster traveling through the air, for example.

10. You are trying to move a box across a surface but it does not budge. What can you say about friction in such a case?

a. Static friction exceeds kinetic friction b. Kinetic friction exceeds static friction c. Static friction must be infinite d. Kinetic friction must be absent

Answer: a. Static friction in such cases must exceed kinetic friction because the object is not moving. Static friction is overcome and the kinetic friction becomes the operative friction force when the object becomes a moving object.