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3 years ago

What is pollen formation and where does it occur?

Physics

1 answer:

arsen [322]3 years ago

3 0

Pollen formation is the microsporangia of the male cone (flower) and it occurs on the stigma.

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A 65 kg diver jumps off a diving platform, rises about 1m above the platform, then falls to the pool. What is the divers momentu

leonid [27]

Answer: 0 kgm/s

Explanation: The formulae for momentum is given below as

Momentum = mass × velocity.

The highest point of the diver is simply the point at the maximum height.

Let us assume that the motion of the diver is of a free fall.

For a free fall motion, velocity = 0 m/s and acceleration = - g, where g = 9.8

Hence, at maximum height, v = 0 and m = 65kg hence momentum = 65 × 0 = 0 kgm/s

4 0

3 years ago

A industrial (large) pressure cooker operates at 275 kPa. Initially there is 10 kg of water at 20Â°C, the cooker is operated unt

alex41 [277]

Answer:

$Q_{in} = 25349.92\,kJ$

Explanation:

Let establish a control volume in the industrial pressure cooker, which is a transient state system. From the First Law of Thermodynamics, the heating process is modelled:

$Q_{in} + m_{1}\cdot h_{1} - m_{2}\cdot h_{2} = (m_{1}-m_{2})\cdot u_{2} - m_{1}\cdot u_{1}$

The heat transfered to the cooker is:

$Q_{in} = m_{2}\cdot h_{2} - m_{1}\cdot h_{1} + (m_{1}-m_{2})\cdot u_{2}-m_{1}\cdot u_{1}$

Properties at each state are described below:

State 1

$u_{1} = 83.913\,\frac{kJ}{kg}$

$h_{1} = 83.915\,\frac{kJ}{kg}$

State 2

$u_{2} = 2540.1\,\frac{kJ}{kg}$

$h_{2} = 2720.9\,\frac{kJ}{kg}$

The heat transfered to the cooker is:

$Q_{in} = (9\,kg)\cdot (2720.9\,\frac{kJ}{kg} ) - (10\,kg)\cdot (83.915\,\frac{kJ}{kg} ) + (1\,kg) \cdot (2540.1\,\frac{kJ}{kg} )-(10\,kg)\cdot (83.913\,\frac{kJ}{kg} )$

$Q_{in} = 25349.92\,kJ$

7 0

3 years ago

A certain brand of hot-dog cooker works by applying a potential difference of 120 V across opposite ends of a hot dog and allowi

ivanzaharov [21]

Answer:

The time it will take to cook three hot dogs simultaneously is 2.5 minutes

Explanation:

Here we have, the Energy of electric heating given by Joule heating that is;

P = IV = 120×10 = 1200 J/s = 1.2 kJ/s

Since the energy required to cook one hotdog = 60.0 kJ we have

Energy required to cook three hot dogs = 3 × 60.0 kJ = 180.0 kJ

Therefore, the time required to cook the three hot dogs is

(180.0 kJ)/(1.2 kJ/s) = 150 s

The time it takes to cook three hot dogs simultaneously is

150 seconds or 150/60 minutes which is 2 minutes 30 seconds or 2.5 minutes

5 0

3 years ago

A class 9 student booked his ticket to moon. His travel company

jasenka [17]

Answer: LET'S TAKE GRAVITY ON EARTH AS 10 N/KG AND ON MOON AS 0.6 N/KG

a) weight=15kgx10N/kg

= 150N

b) weight=15x0.6=9N

c) mass=is the same so 15kg

d) mass is measured in kg, weight in NEWTONS OR $KG M/S^{2}$

e) when the gravitational force is zero

Explanation:

7 0

3 years ago

5N of force is applied to move a large nail a distance of 10 cm from an electromagnet on a frictionless table. The nail is then

DedPeter [7]

Answer:

C) The rate of change from potential to kinetic energy is exponential.

Explanation:

As we know that total mechanical energy must be conserved here

As we know that there is no friction force on this system of electromagnet and nail

So here we can say that that

Magnetic potential energy of the nail + electromagnet system will convert into kinetic energy of the nail as it is released.

So we will have

Initial potential energy = work done to move it away by 10 cm

$U = 5(0.10)$

$U = 0.5 J$

now as the nail is released then this potential energy will start to convert into kinetic energy

So here correct answer must be

C) The rate of change from potential to kinetic energy is exponential.

7 0

3 years ago