Below investigations will provide evidence to support the concept that objects can exert forces on other objects without touching through different forces like static electricity and magnetism.
To provide evidence that objects can exert forces on other objects without touching, you would want to conduct investigations that demonstrate different aspects of this concept. Here are three investigations from the options provided (A, B, and D) along with step-by-step explanations:
A. Measuring how close a soda can must be before it rolls toward a balloon that has been rubbed on someone's hair.
Step 1: Set up the experiment.
- Place a table in the classroom.
- Inflate a balloon and rub it against someone's hair to create static electricity.
- Place a soda can on the table.
Step 2: Control variables.
- Ensure the table is level.
- Use the same type of soda can for consistency.
- Use the same person's hair to rub the balloon each time.
Step 3: Experimental procedure.
- Start with the balloon at a certain distance away from the soda can (e.g., 10 meters).
- Gradually move the balloon closer to the soda can while observing its behavior.
- Record the distance at which the soda can starts to roll toward the balloon due to static electricity.
Step 4: Data collection and analysis.
- Record the distance at which the soda can starts moving.
- Repeat the experiment multiple times and calculate an average distance.
- Analyze the results to show that the soda can moved without direct contact, indicating the influence of an invisible force (static electricity).
B. Counting the number of staples that are directly attached to a strong magnet.
Step 1: Set up the experiment.
- Place a strong magnet on a flat surface, such as a table.
- Gather a pile of metal staples.
Step 2: Control variables.
- Use the same type and strength of magnet for consistency.
- Ensure the staples are the same size and composition.
Step 3: Experimental procedure.
- Hold the magnet close to the pile of staples without touching them.
- Observe how many staples are attracted and attach themselves to the magnet.
step 4: Data collection and analysis.
- Count the number of staples attached to the magnet.
- Repeat the experiment with the same magnet and staples multiple times.
- Analyze the results to demonstrate that the staples were attracted to the magnet without direct contact, showing the magnetic force.
D. Placing a magnet against a jar containing a mixture of iron filings and sand.
Step 1: Set up the experiment.
- Obtain a clear glass jar with a lid.
- Create a mixture of iron filings and sand inside the jar.
- Place a strong magnet outside the jar.
Step 2: Control variables.
- Use the same type and strength of magnet for consistency.
- Ensure the mixture of iron filings and sand is consistent in each jar.
Step 3: Experimental procedure.
- Bring the magnet close to the jar without touching it.
- Observe the behavior of the iron filings inside the jar.
Step 4: Data collection and analysis.
- Describe and record what happens to the iron filings as the magnet is brought near the jar.
- Repeat the experiment multiple times.
- Analyze the results to demonstrate that the iron filings were influenced by the magnet's magnetic field without direct contact.