Dennis cannot scratch a mineral sample with his fingernail, but he observes that he can
scratch the mineral sample with a piece of metal. What physical property of the mineral
sample is Dennis investigating?

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

i think the answer is tomato juice? not entirely sure though

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.