All categories

3 years ago

Which of the following statements is true?

Physics

1 answer:

Brums [2.3K]3 years ago

8 0

Answer:

В. An object with mechanical energy is always able to perform work.

Explanation:

Energy can be defined as the ability (capacity) to do work. The two (2) main types of energy are;

a. Gravitational potential energy (GPE): it is an energy possessed by an object or body due to its position above the earth.

b. Kinetic energy (KE): it is an energy possessed by an object or body due to its motion.

Furthermore, the mechanical energy of a physical object or body is the sum of the potential energy and kinetic energy possessed by the object or body and it is measured in Joules.

Mathematically, it is given by the formula;

Mechanical energy = G.P.E + K.E

Hence, the true statement is that an object with mechanical energy is always able to perform work.

You might be interested in

How does Frankenstein's discovery most change him?

iragen [17]

It changes him because it makes people want to find him now

4 0

4 years ago

A capacitor is made from two hollow, coaxial, iron cylinders, one inside the other. The inner cylinder is negatively charged and

kari74 [83]

Answer:

$a. 4.2057\times 10^-^1^2 F \ or 4.2057\ pF\\b. 2.7344V$

Explanation:

Given the permittivity constant to be $8.854\times 10^-^1^2 F/m$ ,The capacitance of a $cylindrical \ capacitor$ of length, $L$ is given by the equation:

$C=\frac{2\pi \epsilon _o L}{ln(b/a)}$ where $b$ is the radius of the outer cylinder and $a$ the radius of the inner cylinder.

The values are given as: $a=0.550mm(5.5\times 10^-^4m), \ b=4.00mm(4.0\times10^-^3m), \ L=15.0cm(0.150m)$

Substitute in our capacitance equation:

$C=\frac{2\times\pi \times 8.854\times 10^-^1^2 \times 0.15}{In(4.00/0.550)}\\=4.2057\times 10^-^1^2 F$

Hence the capacitance is $4.2057\times 10^-^1^2 F$

b. The charge on the capacitance is related to the potential difference across it. The potential difference is expressed using the equation:

$Q=CV$ , $Q=11.5pC$

From a above, we already have our capacitance value, $C=4.2057\times 10^-^1^2 F$

We substitute $C$ in the pd equation:

$v=>(11.5)/(4.2057)\\=2.7344V$

Hence, the applied potential difference is 2.7344V

4 0

3 years ago

A block is projected up a frictionless inclined plane with initial speed v0 = 7.14 m/s. The angle of incline is θ = 36.5°. (a) H

Wewaii [24]

Answer:

$(a)x=4.37m\\\\(b)t=1.225s\\\\(c) v_{f}=7.14m/s$

Explanation:

Given data

$v_{o}=7.14m/s\\\alpha =36.5^o$

For Part (a)

Starting with the -ve acceleration of the body (opposite to the gravitational force)

$a=-gSin\alpha \\a=-(9.8m/s^2)Sin(36.5)\\a=-5.83m/s^2$

Using equation of motion

$v_{f}^2=v_{o}^2+2ax\\(0m/s)^2=(7.14m/s)^2+2(-5.83m/s^2)x\\-(7.14m/s)^2=2(-5.83m/s^2)x\\x=\frac{-(7.14m/s)^2}{2(-5.83m/s^2}\\ x=4.37m$

For Part (b)

Using the result in Part (a) we can substitute in other equation of motion to get time t:

$x=\frac{1}{2}vt\\ 4.37m=\frac{1}{2}(7.14m/s)t\\ (7.14m/s)t=2*(4.37)\\t=8.744/7.14\\t=1.225s$

For Part (c)

At state 2 where vo=0m/s and the acceleration is positive (same direction as the gravitational force)

$a=gSin\alpha \\a=(9.8m/s^2)Sin(36.5)\\a=5.83m/s^2\\\\\\v_{f}^2=v_{o}^2+2ax\\v_{f}^2=(0m/s)^2+2(5.83m/s^2)(4.37m)\\v_{f}^2=50.95\\v_{f}=\sqrt{50.95}\\ v_{f}=7.14m/s$

4 0

3 years ago

Which statements describe acceleration? Check all that apply.

DiKsa [7]

Answer:

Negative acceleration occurs when an object speeds up in the negative direction.

Positive acceleration occurs when an object speeds up in the positive direction.

Explanation:

This might be wrong but I get some points for a answer..

8 0

3 years ago

The 4.5 cm long second hand on a watch rotates smoothly. What is its angular velocity? What is the speed of the tip of the hand?

Vlada [557]

Angular velocity means how many radians/degrees is this hand passing by every second.
First, you realize it goes through a whole revolution (2 $\pi$ in radians) in 60 seconds.
This means for every second, it passes by:
$\frac{2 \pi }{60 s} = 0.105 \frac{rad}{sec}$

For the next part, you need to know this equation:
Tangential velocity=Angular velocity x radius (meters)
$velocity=0.105 \frac{rad}{sec} *0.045m$
$velocity=0.004725 \frac{meters}{sec}$

5 0

3 years ago