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DiKsa [7]
3 years ago
10

1pt Which is an observation? O A. A person hears the song of a bird. OB. A person suggests that bird calls are a means of commun

ication. O C. A person concludes that bird calls attract mates. OD. A person writes a paper describing different kinds of bird calls....​

Physics
1 answer:
Doss [256]3 years ago
3 0

Answer:

D

Explanation:

he describes as he writes them down

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You wish to buy a motor that will be used to lift a30-kg bundle of shingles from the ground to the roof of a house. The shingles
hodyreva [135]

Answer:

the minimum value of torque is 101.7 N-m.

Explanation:

Given that,

Mass of bundle of shingles, m = 30 kg

Upward acceleration of the shingles,

The radius of the motor of the pulley, r = 0.3 m

Let T is the tension acting on the shingles when it is lifted up. It can be calculated as :

T-mg=ma

T=m(g+a)

T=10\times (9.8+1.5)\\T = 113 N

Let \tau is the minimum torque that the motor must be able to provide. It is given by :

\tau=r\times T\tau=0.3\times 339\tau=101.7\ N-m

the minimum value of torque is 101.7 N-m.

6 0
3 years ago
Briefly outline the caloric theory about the nature of heat
Stells [14]
Briefly outline the caloric theory about the nature of heat
4 0
3 years ago
A positively charged particle initially at rest on the ground accelerated upward to 100m/s in 2.00s. If the particle has a charg
VashaNatasha [74]

Answer:

Explanation:

From the question we are told that

     The initial velocity is  u  =  100 m/s

       The time taken is  t = 2.0 s

       The charge to mass ratio is  Q/m  =  0.100 C/kg

       

Generally the acceleration is mathematically evaluated as

              a  =   \frac{u}{t }

substituting values  

               a =   \frac{100}{2}

                a =  50 \ m/s^2

The electric field is mathematical represented as

             E = \frac{(a+g)}{Q/m}

substituting values

              E = \frac{(50+9.8)}{0.100}

              E = 598 \ N/C

4 0
3 years ago
Which of the following statements are true concerning the creation of magnetic fields?
Soloha48 [4]

Answer:

A moving electric charge creates a magnetic field at all points in the surrounding region.

An electric current in a conductor creates a magnetic field at all points in the surrounding region.

A permanent magnet creates a magnetic field at all points in the surrounding region.

Explanation:

Magnetic field can be produced by:

- moving charges (i.e. a moving electron, or a current in a conductor)

- A magnet

The strength of the magnetic field produced by a current-carrying wire is

B=\frac{\mu_0 I}{2\pi r}

where

I is the current

r is the distance from the wire

As we see from the formula, the magnetic field is produced at all points in the surrounding region, because B becomes zero only when r becomes infinite. The same is true for the magnetic field created by a single moving charge or by a magnet.

The following choices instead are not correct:

- A single stationary electric charge creates a magnetic field at all points in the surrounding region.

- A distribution of electric charges at rest creates a magnetic field at all points in the surrounding region.

Because they involve the presence of stationary charges, and stationary charges do not produce magnetic fields.

3 0
3 years ago
A 57-gram tennis ball moving at 70 miles per hour is hit with a 110-gram tennis racquet moving at 60 miles per hour. Which state
Whitepunk [10]

Answer:

D. Because mass and energy are both conserved, the total amounts of mass and energy are the same before and after impact.

Explanation:

As we know that, the energy in motion is Kinetic Energy mathematically given as:

KE=\frac{1}{2} m.v^2

<u>Now, according to the law of conservation of energy:</u>

\frac{1}{2} m_1.u_1^2+\frac{1}{2} m_2.u_2^2=\frac{1}{2} m_1.v_1^2+\frac{1}{2} m_2.v_2^2

where:

m_1\ \&\ m_2 mass of racquet and ball respectively and u_1\ \&\ u_2 are their respective initial velocities.

v_1\ \&\ v_2 are the respective final velocities.

<u>Also the law of conservation of momentum is applicable in this case:</u>

m_1.u_1+ m_2.u_2= m_1.v_1+m_2.v_2

In this case the velocity of the lighter mass will get increases in the final condition.

5 0
3 years ago
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