A0.5-kg uniform meter stick is suspended by a single string at the 30-cm mark. a 0.2-kg mass hangs at the 80 cm mark. what mass hung at the 10-cm mark will produce equilibrium?

0.50 kg

Explanation:

From the equilibrium condition, torques must be balanced. Torque is the product of force and distance.

The unknown mass is at a distance of 20 cm from the suspension point (30 cm). The 0.20 kg is at a distance of 0.50 cm from that same point.

Clockwise torques must equal anti clockwise torques.

So (0.20 m)  (M g) = (0.50 m)(0.20 g)

Here M is the unknown mass and g stands for gravity.

⇒ Unknown mass = M = (0.50 × 0.20 ) ÷ (0.20)= 0.50 kg

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.