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3 years ago

Please help me with this question...

Physics

2 answers:

Yakvenalex [24]3 years ago

7 0

1) In first case, both the objects(hand & tea) are in direct contact, so heat will flow by the process of "Conduction"

2) In this case, objects are not in direct contact, and heat is transferring from one to another by "Convection"

3) Here, there is no contact between the objects (our body & sun), sun light with heat comes through the process of "Radiation"

In short, Your Answers would be:
1) Conduction
2) Convection
3) Radiation

Hope this helps!

Arturiano [62]3 years ago

4 0

The first is conduction.

This comes as the hot water spills on to your hand through contact.

The second is convection. The hot air rising is due to convection currents being set up.

The third is radiation. This is heat transfer through space.

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Why does a child in a wagon seem to fall backward when you give the wagon a sharp pull forward? 15. What force is needed to acc

slavikrds [6]

Answer:

Force, F = 77 N

Explanation:

A child in a wagon seem to fall backward when you give the wagon a sharp pull forward. It is due to Newton's third law of motion. The forward pull on wagon is called action force and the backward force is called reaction force. These two forces are equal in magnitude but they acts in opposite direction.

We need to calculate the force is needed to accelerate a sled. It can be calculated using the formula as :

F = m × a

Where

m = mass = 55 kg

a = acceleration = 1.4 m/s²

$F=55\ kg\times 1.4\ m/s^2$

F = 77 N

So, the force needed to accelerate a sled is 77 N. Hence, this is the required solution.

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3 years ago

A common physics demonstration is to drop a small magnet down a long, vertical aluminum pipe. Describe the motion of the magnet

Rzqust [24]

Answer and Explanation:

This experiment is known as Lenz's tube.

The Lenz tube is an experiment that shows how you can brake a magnetic dipole that goes down a tube that conducts electric current. The magnet, when falling, along with its magnetic field, will generate variations in the magnetic field flux within the tube. These variations create an emf induced according to Faraday's Law:

$\varepsilon =-\frac{d\phi_B}{dt}$

This emf induced on the surface of the tube generates a current within it according to Ohm's Law:

$V=IR$

This emf and current oppose the flux change, therefore a field will be produced in such a direction that the magnet is repelled from below and is attracted from above. The magnitude of the flux at the bottom of the magnet increases from the point of view of the tube, and at the top it decreases. Therefore, two "magnets" are generated under and above the dipole, which repel it below and attract above. Finally, the dipole feels a force in the opposite direction to the direction of fall, therefore it falls with less speed.

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3 years ago

Read 2 more answers

The Millersburg Ferry (m = 13000.0 kg loaded) is travelling at 11 m/s when the engines are put in reverse. The engineproduces a

Pie

Explanation:

It is given that,

Mass of Millersburg Ferry, m = 13000 kg

Velocity, v = 11 m/s

Applied force, F = 10⁶ N

Time period, t = 20 seconds

(a) Impulse is given by the product of force and time taken i.e.

$J=F.\Delta t$

$J=10^6\ N\times 20\ s$

$J=2\times 10^7\ N-s$

(b) Impulse is also given by the change in momentum i.e.

$J=\Delta p=p_f-p_i$

$J=p_f-p_i$

$p_f=J+p_i$

$p_f=2\times 10^7\ N-s+13000\ kg\times 11\ m/s$

$p_f=20143000\ kg-m/s$

(c) For new velocity,

$v_f=\dfrac{p_f}{m}$

$v_f=\dfrac{20143000\ kg-m/s}{13000\ kg}$

$v_f=1549.46\ m/s$

Hence, this is the required solution.

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3 years ago

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An 100 kg object traveling at 50 m/s collides (perfectly inelastic) with a 50 kg object initially at rest.

qaws [65]

Answer:

Option C. 5,000 kg m/s

Explanation:

<u>Linear Momentum on a System of Particles </u>

Is defined as the sum of the momenta of each particles in a determined moment. The individual momentum is the product of the mass of the particle by its speed

P=mv

The question refers to an 100 kg object traveling at 50 m/s who collides with another object of 50 kg object initially at rest. We compute the moments of each object

$m_1=(100\ kg)(50\ m/s)=5,000\ kg\ m/s$