Chapter 2: Magnetism and Electromagnetism

First and Last Name

How can the girl increase the acceleration of the cart without changing the force she exerts?

• A take the wheels off the cart
• B take the object off the cart
• C take her shoes off
• D put the cart on top of the object

A student places a bar magnet 5 cm from an iron paper clip and observes no movement of the paper clip. The student decreases the distance between the magnet and paper clip and records any change to the paper clip in a table. Which action will allow the student to observe a force between the magnet and the paper clip?

• A Replace the iron paper clip with a plastic paper clip.
• B Return the distance between the magnet and the paper clip to 5 cm.
• C Reduce the distance between the magnet and the paper clip to less than 3 cm.
• D Replace the magnet with a larger and weaker magnet.

A block moves in the direction of a plant with the force, FA. The other forces acting on the block include the normal force, FN; the force of friction, FF; and the force of gravity, FG. Which diagram best represents the forces on the block as it moves toward the plant?

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A crane uses an electromagnet to move large metal objects in a junkyard. A student develops different designs of an electromagnet to act as a model for improving the electromagnet on a crane. Each design uses a battery and copper wire wrapped around an iron cylinder. The table shows the number of iron pins attracted by each design. Which design changes will cause the strength of a crane’s electromagnet to increase?

• A decreasing the voltage and increasing the number of wire loops
• B decreasing the voltage and decreasing the number of wire loops
• C increasing the voltage and increasing the number of wire loops
• D increasing the voltage and decreasing the number of wire loops

A student develops a model of an electric motor using two pins, a wire coil, a battery, tape, and a magnet, as shown. The student provides a slight push to the wire coil, and then the coil continues to spin with a certain speed. How can the student increase the speed of the electric motor?

• A by using wider pins
• B by using thinner pins
• C by using less wire in the coil which would allow fewer loops
• D by using more wire in the coil which would allow more loops

To reverse the direction of current in a motor, current is conducted

• a. through the armature.
• b. in the direction of rotation.
• c. through the brushes to the commutator.
• d. through the commutator to the armature.

The position of an object is tracked over time. Which statement about the motion of this object is correct?

• A The object turned around and sped back to its original location at the 9-second mark.
• B The object started from rest and had a speed of 10 m/s over a 5-second period.
• C The object was moving slower at the 4-second mark than it was at the 12-second mark.
• D The object had a velocity that was constant for the first 5-second period.

A student develops a model of an electromagnet using an iron nail coiled with several turns of insulated wire. The ends of the wire are connected to a battery. The nail attracts several paper clips from a pile. The student uses four different batteries and records the number of paper clips picked up in a table. Which battery increases the strength of the electromagnet the most?

• A Battery 1
• B Battery 2
• C Battery 3
• D Battery 4

Circular magnets are placed under a table that is covered in iron filings. The iron filings move to match the shape of the magnets, as shown. Which two observations show why the movement of the iron filings demonstrates a noncontact force?

• A The iron filings and magnets are not touching.
• B The iron filings move because of a magnetic field.
• C The magnets are larger than the iron filings.
• D The magnets have a higher mass than the iron filings.
• E The iron filings and magnets are made of a metal.