The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction.
The 4 m board's center of mass is 2 m so the pivot point is somewhere between Tasha and 2 m (if you draw a picture it's going to make this clearer)
The mass of Tasha * her distance from the pivot point = the board's mass * distance from the pivot point.
<span> Let d1 be the distance Tasha is from the pivot point. The board's center of mass from the pivot point is 2 m - d1
</span><span> 20 kg * d1 = 10 kg * (2m - d1)
</span><span> Solve for d1, you should get 2/3 of a m for the distance Tasha is from the pivot or support point. The center of mass for the board is 1 1/3 m from the support point. </span>
Answer:
Few millimeter thick aluminium, water, wood, acrylic glass or plastic.
Explanation:
The materials that are best for protection against beta particles are few millimeter thickness of aluminium, but for the high energy beta-particles radiations the low atomic mass materials such as plastic, wood, water and acrylic glass can be used.
These materials can also be used in personal protective equipment which includes all the clothing that can be worn to prevent any injury or illness due to the exposure to radiation.
