A box of mass m is pulled with a constant acceleration a along a horizontal frictionless floor by a wire that makes an angle of 15° above the horizontal. If T is the tension in this wire, then .

A) T = ma.
B) T > ma.
C) T < ma.

B) T > ma.

Explanation:

To solve this problem, we have to analyze the forces acting in the horizontal direction.

In the horizontal direction, we have:

- The horizontal component of the tension in the wire, , where T is the magnitude of the tension and the angle that the wire makes with the horizontal

Since this is the only force acting on the box in the horizontal direction, this is also the net force, so it is equal to the product of mass and acceleration (Newton's second law of motion):

where

m is the mass of the box

a is the acceleration

We can rewrite the equation as

The angle in this problem is , so

Therefore, the correct option is

B) T > ma.

(75°f − 32) × 5/9 = 23.889°c

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia