University:
California State University, Los Angeles
Course:
PHYS 1100 | Physics
Academic year:

2021
Views:

308

Pages:

3
Author:

Alma Stephenson

Quiz: Introduction to Forces Read each question. Circle the letter of the correct answer. 1. What is gravity? A. a contact force B. a frictional force C. a magnetic force D. a noncontact force 2. Which of these is considered a contact force? A. the force between two magnets B. the gravitational pull of a planet C. the friction between an object and air D. the force between two charged particles 3. A box has two forces acting on it. One force is 100 N upward. Another force is 50 N downward. What is the net force on the box? A. 50 N upward B. 100 N upward C. 50 N downward D. 100 N downward 4. Melanie watched the path a baseball followed after a pitcher threw it. She noticed that the ball traveled horizontally away from the pitcher as well as downward toward the ground. What force caused the ball to accelerate in the downward direction when it was thrown? A. applied force B. air resistance C. electrical force D. gravitational force 5. Why are some forces considered to be noncontact forces? A. Objects must be far apart in order to exert a force. B. Objects do not have to touch each other to experience a force. C. Objects push each other apart to increase the distance between them. D. Objects must be large in size in order to exert a force that is strong enough to notice. 6. Why is the friction force considered to be a contact force? A. Friction affects only solid objects. B. Friction always acts in the same direction. C. Friction is produced when objects slide past one another. D. Friction acts in a direction opposite to the direction of an object’s motion. 7. Why is the magnetic force considered to be a noncontact force? A. Magnets must be far apart in order to exert a force. B. Magnets do not have to touch each other to experience a force. C. Magnets push each other apart to increase the distance between them. D. Magnets must be large in size in order to exert a force that is strong enough to notice. Read each statement. Write your answer on the lines. 8. A bird flies at 12.5 meters per second. The wind speed is 4.5 meters per second. What is the speed of the bird when it flies with the wind? What is the speed of the bird when it flies against the wind? 9. Marek is trying to push a box of sports equipment across the floor. The arrow on the box is a vector showing the force Marek exerts. Describe all the forces acting on the box. Explain what needs to happen for the box to start moving. 10. The diagram shows the forces acting on a box. Explain how to calculate the net force in any direction on the box. Determine the net force upward or downward. Determine the net force to the right or left. Predict how the box will move.