Science grade 7 - Chapter 8 review

Two weights, A and B, are placed on opposite ends of a pivot. In which of the following situations is it IMPOSSIBLE for the moments to be balanced?

• A weighs more than B and is closer to the pivot than B

• A weighs less than B and is further from the pivot than B

• A weighs more than B and is further from the pivot than B

• A and B weigh the same and they are the same distance from the pivot

Which are two forces acting on a boat when it floats motionless in the sea?

• Gravity and air resistance

• Upthrust and normal force

• Friction and magnetic force

• Gravity and upthrust

Akira sits on a see-saw. He sits 2 m from the pivot and his weight is 50 N. Calculate the moment. Include the correct unit in your answer!

Nadia uses a screwdriver to open a tin of paint. The screwdriver is 0.3 m long and she applies 5 N of force. Calculate the moment. Include the unit in your answer!

Taksheel opens a door. The handle is 20 cm long and he applies 4 N of force. Calculate the moment. Include the correct unit in your answer!

Two people pull on opposite ends of a rope. They pull with the same force. What happens?

• The rope starts to move to the left

• The rope stays still in the middle

• The rope starts to move to the right

• The rope changes color

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-1

Mi wears shoes with an area of 0.05 square meters. She weighs 45 Newtons. Calculate the pressure (in Newtons per square meters) she exerts on the ground. DO NOT include the unit in your answer!

The spreading out of particles from a region where there are lots of them to a region where there are fewer of them is called ....

Which container filled with gas would have the highest pressure?

• A cold container with a large amount of gas

• A cold container with a small amount of gas

• A hot container with a large amount of gas

• A hot container with a small amount of gas

Tags

NGSS.HS-PS3-2

Dogs pull a sledge over a flat, icy surface. Their pulling force is 240 N forwards. Air resistance is 160 N and the friction from the sledge on the ice is 60 N. What can be said about the resultant force?

• The resultant force is 20 N backwards

• The resultant force is 20 N forwards

• The resultant force is 140 N forwards

• The resultant force is 140 N backwards

Tags

NGSS.MS-PS2-2