3rd Grade Science : Physical Science

Study concepts, example questions & explanations for 3rd Grade Science

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Example Questions

Example Question #4 : Investigate How Unbalanced Forces Affect An Object's Motion

Mrs. Gartrell's class is playing Tug-of-War to demonstrate how an unbalanced force will affect an object's motion. The class has twenty students, and they have to split into teams to represent an unbalanced force. J'Michael says they should divide evenly, ten on each side. Nate disagrees and says there should not be even teams; it should be the eight students against twelve students.

Who is correct, and why?

Possible Answers:

Neither student is correct. Their suggestions would not demonstrate an unbalanced force. They would need to change their set-up to have unbalanced forces.

They are both correct. Both of their ideas would work to show an example of an unbalanced force.

Nate is correct. Dividing the team into uneven numbers and uneven sizes will give one side more strength, which represents an unbalanced force.

J'Michael is correct. If the teams are split ten and ten, there will be equal strength on each side, which represents an unbalanced force.

Correct answer:

Nate is correct. Dividing the team into uneven numbers and uneven sizes will give one side more strength, which represents an unbalanced force.

Explanation:

In this situation, the students are trying to demonstrate an example of unbalanced forces. Unbalanced forces mean they are not even or the same. One side should have more energy than another when there are unbalanced forces. Nate is correct in this scenario; there should be uneven teams with different strengths on each side. To get the rope to move and one team to win, there has to be more strength on one side. When creating the teams, the side with the highest number of students would have more energy and strength, leading to an unbalanced force.

 

Example Question #12 : Balanced And Unbalanced Forces

A toy train is rolling on a smooth surface. I am investigating how unbalanced forces affect an object's motion, so I push a heavy car into the train and then repeat it again but with a lighter car. What effect on the train's motion will I most likely notice?

Possible Answers:

Neither car will affect the train's motion.

The heavier car will change the train's direction or speed more than the lighter car will.

The heavier car will change the train's direction or speed the same as the lighter car will.

The lighter car will change the train's direction or speed more than the heavier car will.

Correct answer:

The heavier car will change the train's direction or speed more than the lighter car will.

Explanation:

In this scenario, there is an example of unbalanced forces. When an unbalanced force is applied to an object, there can be a change in motion. When the heavier toy car moves into the path or side of the train, it will cause the little vehicle to change speeds, directions, or even stop. This change in motion is due to a stronger force acting upon the toy train. The lighter car may have an impact on the train's movement, but it will not be as great.

Example Question #1 : Investigate How Unbalanced Forces Affect An Object's Motion

Which scenario is NOT an example of unbalanced forces?

Possible Answers:

Patrick pushes a vase off of the countertop.

Steven pulls a door open so his mother can walkthrough.

Samantha and her twin sister play tug-of-war; it ends in a tie.

Jeffery and his little brother crash into each other while rollerblading.

Correct answer:

Samantha and her twin sister play tug-of-war; it ends in a tie.

Explanation:

In the scenarios, "Samantha and her twin sister play tug-of-war; it ends in a tie." is NOT an example of unbalanced forces. The sisters are the same age, and we can assume the same size (they are twins) and the game neds in a tie. This means that they pulled with the same strength, and neither won. This would indicate that the forces were balanced during the tugging.

Example Question #1 : Investigate How Unbalanced Forces Affect An Object's Motion

Unbalanced forces are the opposite of a balanced force.

Possible Answers:

True

False

Correct answer:

True

Explanation:

An unbalanced force causes a change in motion, speed, direction, or movements because of unequal force or strength that is applied to one side of an object. Opposite sides have forces acting against them, but in the case of unbalanced forces, one side has more energy than the other. Unbalanced forces are the opposite of a balanced force.

Example Question #1 : Question Cause/Effect Relationships Of Electricity

When you rub a balloon on your hair, it creates static electricity. What happens to your hair when you take the balloon off of your head?

Possible Answers:

Your hair is not affected by the balloon when it isn't touching your head.

Your hair sticks out in the direction of the balloon when it isn't touching your head.

Your hair looks greasy and dirty after the balloon is removed from your head.

Your hair is repelled by the balloon when it isn't touching your head.

Correct answer:

Your hair sticks out in the direction of the balloon when it isn't touching your head.

Explanation:

When static electricity is created between a balloon and your hair, your hair is attracted to the balloon. If you simply let go of the balloon, it will stay on your head! If you take the balloon off your head, your hair will follow the direction of the balloon and stick straight out.

Example Question #1 : Question Cause/Effect Relationships Of Electricity

Lightning is an example of static electricity. The clouds in the sky are both positively and negatively charged, creating a bolt of energy. What is true about the clouds that produce lightning?

Possible Answers:

The clouds must not be raining to create lightning.

The clouds have to be touching to create lightning.

The clouds do not have to be touching to create lightning.

The clouds must be raining to create lightning.

Correct answer:

The clouds do not have to be touching to create lightning.

Explanation:

If one cloud is positively charged and one is negatively charged, lightning can be created even if there is a gap between the clouds. The particles are active enough to generate electricity through lightning, even if there is no contact between the positive and negative clouds. For lightning to be created, it does not matter if it is raining or not. It also does not matter if the clouds are touching. This is also true of oppositely charged objects on a smaller scale, like hair sticking to a balloon.

Example Question #3 : Question Cause/Effect Relationships Of Electricity

Every time I take clothes out of the dryer, they are all stuck together. My socks are attached to my shirts, and when I pull them apart, I hear a crackling noise.

What is causing this to happen?

Possible Answers:

Sound waves

Magnetism

Radio waves

Static electricity

Correct answer:

Static electricity

Explanation:

The reason this happens is because of static electricity. In the dryer, different fabrics rub together, the electrons from a cotton sock may rub off onto a polyester shirt. That's why clothes sometimes stick together and make sparks when you pull them apart.

Example Question #54 : Physical Science

When discussing electric charges it is true that opposites _________.

Possible Answers:

repel

attract

jump

do nothing

Correct answer:

attract

Explanation:

Negative electrons and positive protons are opposite charges and are attracted to each other. An example would be if a balloon has the opposite charge as someone's hair, and they are held near each other. The hair will stand up and stretch out towards the balloon because the opposite charges are attracted to each other.

Example Question #2 : Question Cause/Effect Relationships Of Electricity

Cheri scoots her feet across the carpet while she is wearing cotton socks. She generates a negative charge and reaches to touch the positively charged doorknob. Static electricity is formed.

What will happen when she touches the doorknob?

Possible Answers:

She will be shocked because of similar charges.

She will be shocked because of the opposite charges.

She will not be shocked because of the opposite charges.

Nothing will happen; it is just a doorknob that she is touching.

Correct answer:

She will be shocked because of the opposite charges.

Explanation:

When someone rubs their feet across the carpet, there is a build-up of static electricity. Your feet are rubbing negatively charged electrons off of the floor, and it leaves you with a slightly negative charge. When you reach the positively charged knob, the electrons jump and cause the static shock that you feel on your fingertips. The opposite charges are attracted to each other.

Example Question #3 : Question Cause/Effect Relationships Of Electricity

Mr. Figueroa's class is exploring the cause and effect relationships of electricity. He asks the class to think about a balloon being rubbed on someone's hair and then held up to small bits of paper.

Which of the following is true regarding the static electricity between the paper and the balloon?

Possible Answers:

The two objects can have the same electric charge and still be attracted.

The two objects must be touching each other to be attracted.

The two objects can be separated and still attracted to each other.

The two objects must be different colors to have an electric pull.

Correct answer:

The two objects can be separated and still attracted to each other.

Explanation:

Mr. Figueroa is providing an example of how two objects do not need to be touching for there to be an attraction. The static electricity generated by rubbing the balloon on someone's hair is the opposite charge as the charge on the paper. When the paper and balloon come near each other (not touching), the different charges are attracted to each other, and the balloon will cause the paper to "jump" or move.

 

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