In which of the following methods of heat transfer is it necessary for the objects to be directly touching one another?

The trajectory of a projectile always ________________.

sattari [20]

Answer:

c) curves downward, below the initial velocity vector

Explanation:

A projectile is usually launched from a height, where it is launched with an initial velocity. From that point the gravitational force begins to act on the projectile causing it to decay. As time passes, the projectile advances but its height decreases. So its trajectory is curved downward, below the initial velocity vector.

8 0

2 years ago

The amount of work done against friction to slide a box in a straight line across a uniform, horizontal floor depends most on th

Ivenika [448]

Amount of force that is applied to the box

7 0

2 years ago

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Could you please explain to me Newton's second law of motion? Please I don't get it :/

MissTica

Answer:

Newton's second law states that when a body of mass m is accelerated with force f

then F=ma

this means acceleration of an object depends on both force with which it is moving as well as its mass

8 0

2 years ago

Is it proper to use an infinitely long cylinder model when finding the temperatures near the bottom or top surfaces of a cylinde

Gelneren [198K]

Answer:

No, it is not proper to use an infinitely long cylinder model when finding the temperatures near the bottom or top surfaces of a cylinder.

Explanation:

A cylinder is said to be infinitely long when is of a sufficient length. Also, when the diameter of the cylinder is relatively small compared to the length, it is called infinitely long cylinder.

Cylindrical rods can also be treated as infinitely long when dealing with heat transfers at locations far from the top or bottom surfaces. However, it not proper to treat the cylinder as being infinitely long when:

* When the diameter and length are comparable (i.e have the same measurement)

When finding the temperatures near the bottom or top of a cylinder, it is NOT PROPER TO USE AN INFINITELY LONG CYLINDER because heat transfer at those locations can be two-dimensional.

Therefore, the answer to the question is NO, since it is not proper to use an infinitely long cylinder when finding temperatures near the bottom or top of a cylinder.

8 0

2 years ago

A block sliding across a level surface has a mass of 2.5 kg and a mechanical energy of 20 joules. What is its velocity?

tia_tia [17]

Hi!

The energy of the block is 4 m/s

To calculate this, you need to use the equation for kinetic energy. The block is sliding (i.e. it's moving). If the object is sliding across a level surface, the only energy it has is kinetic energy, because there is no change in potential energy (which changes with height). So, the mechanical energy will be pure kinetic energy. The equation is the following, derived from the expression for kinetic energy:

$v= \sqrt{ \frac{2*Ke}{m}}=\sqrt{ \frac{2*20 (kg*m^{2}*s^{-2}) }{2,5kg}}=4 m/s$

Have a nice day!

8 0

3 years ago