MINI-ASSESSMENT #4: Speed, Forces and Matter

A student pushes a box with 15 N of force to the right. Another student pushes with 5 N to the left. What is the net force, and in which direction?

• 20 N to the left

• 10 N to the right

• 20 N to the right

• 10 N to the left

Answer explanation

To find the net force, subtract the left force (5 N) from the right force (15 N): 15 N - 5 N = 10 N. The net force is 10 N to the right.

Tags

NGSS.MS-PS2-2

Which of the following is an example of balanced forces?

• A ball rolling faster down a hill

• A car slowing down

• A book sitting still on a desk

• A rocket launching

Answer explanation

Balanced forces occur when all forces acting on an object are equal, resulting in no movement. A book sitting still on a desk has equal forces acting on it (gravity and the normal force), making it an example of balanced forces.

A bike travels 80 meters in 10 seconds. What is its average speed?

• 8 m/s

• 70 m/s

• 90 m/s

• 10 m/s

Answer explanation

To find the average speed, divide the distance by the time. Here, average speed = 80 meters / 10 seconds = 8 m/s. Thus, the correct answer is 8 m/s.

Mia and Scarlett are at the grocery store. Why is it harder for Mia to push a full shopping cart than an empty one with the same force?

• The full cart has less air

• The empty cart has more energy

• The full cart has more mass, so it requires more force

• The empty cart has more friction

Answer explanation

Mia finds it harder to push a full cart because it has more mass. According to Newton's second law, more mass requires more force to accelerate, making it more difficult to push compared to an empty cart.

Tags

NGSS.MS-PS2-2

Arjun is observing different states of matter in his science class. He notices that one state has particles that move freely and spread out to fill the entire container. Which state of matter is Arjun observing?

• Solid

• Liquid

• Gas

• Plasma

Answer explanation

Arjun is observing gas, as its particles move freely and spread out to fill the entire container. In contrast, solids have fixed shapes, and liquids take the shape of their container but do not fill it completely.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which of the following is made of only one kind of atom?

• Salt (NaCl)

• Water (H₂O)

• Iron (Fe)

• Air

Answer explanation

Iron (Fe) is a pure element made of only one kind of atom, while salt (NaCl) and water (H₂O) are compounds made of different atoms, and air is a mixture of gases.

Tags

NGSS.MS-PS1-1

Elijah is conducting a science experiment where he combines sand, salt, and water in a beaker. What type of matter did he create?

• Element

• Compound

• Solution

• Mixture

Answer explanation

Elijah created a mixture because he combined sand, salt, and water without chemically altering them. Each component retains its properties, making it a physical combination rather than a compound or solution.