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Veseljchak [2.6K]

3 years ago

12

(ANSWER NOW PLS) A diver with a mass of 90kg is at a height of 10m, and he has not jumped off of the board yet (v=0m/s) what's h

is kinetic energy?

1 answer:

Korolek [52]3 years ago

3 0

Answer: there is zero kinetic energy but there is Gravitational Potential Energy (GPE) and GPE = 8826.3 J

Explanation:

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4. The Mariana trench is in the Pacific Ocean and has a depth of approximately 11,000 m. The density of seawater is approximatel

Alex73 [517]

Explanation:

It is known that relation between pressure and density is as follows.

P = $\rho gh$

where, P = pressure

$\rho$ = density

g = acceleration due to gravity

h = height

Putting the given values into the above formula as follows.

P = $\rho gh$

= $1025 \times 9.8 \times 11000$

= 110495000 Pa

Now, relation between pressure and force is as follows.

P = $\frac{F}{A}$

or, F = PA

F = $110495000 \times \pi \times (0.1)^{2}$

= $3.47 \times 10^{6} N$

Thus, we can conclude that a force of $3.47 \times 10^{6} N$ can be experienced at such depth.

3 0

2 years ago

5. A family of ducks is swimming in a pond at a speed of 3 m/s when a gust of wind hits them. By the time they reach the other s

ella [17]

Answer:

The time taken by the duck to cross the lake is, t= 4 s

Explanation:

Given data,

The initial speed of the ducks, u = 3 m/s

The final speed of the ducks, v = 7 m/s

The acceleration of the duck, a = 1 m/s²

The formula for the acceleration is,

a = (v - u) / t

∴ t = (v - u) / a

Substituting the given values in the above equation,

t = (7 - 3) / 1

= 4 s

Hence, the time taken by the duck to cross the lake is, t= 4 s

6 0

3 years ago

A 1400 kg car is traveling east on the highway at 31 m/s and collides into the rear of a slower moving pickup truck of 2400 kg,

zloy xaker [14]

Answer: 31 m/s due east

Explanation: this question can be solved using the law of conservation of linear momentum.

This law states that in a closed or isolated system, during collision, the vector sum of momentum before collision equals the vector sum of momentum after collision.

Momentum = mass × velocity

From our question, our parameters before collision are given below as

Mass of car = mc = 1400kg

Speed of car =vc = 31 m/s (due east)

Mass of truck = mt = 2400kg

Velocity of truck = vt = 25 m/s ( due east )

After collision

Velocity of car = ?

Velocity of truck = 34 m/s ( due east )

Vector sum of momentum before collision is given as

1400 (31) + 2400 (25) = 43400 + 60000 = 103400 kgm/s

After collision the truck is seen to move faster (v = 34 m/s) which implies that the car also moves due east .

1400 (v) + 2400(25) .... A positive value is between both momenta because they are in the same direction.

After collision, we have that

1400v + 60000

Vector sum of momentum before collision = vector sum of momentum after collision

103400 = 1400v + 60000

103400 - 60000 = 1400v

43400 = 1400v

v = 43400/ 1400

v = 31 m/s due east

4 0

3 years ago

620 J of heat is added to the cylinder of an engine, which causes the gas inside to expand. As a result, the piston of the engin

Maru [420]

Answer:

<u>400</u> J work is done BY the engine.

The internal energy of the gas is <u>620</u> J

Explanation:

The given information are;

The heat added to the cylinder = 620 J

The force applied by the piston of the engine = 8.0 kN = 8,000 N

The distance over which the force moves (the piston) = 5.0 cm = 0.05 m

The work done (by the engine) = Force × Distance = 8,000 N × 0.05 m = 400 J

The internal energy is the sum of the kinetic and potential energy of the system

Therefore, given that the internal energy, U, is the sum total of the energy in the system

∴ U = The heat supplied to the system = 620 J

Which gives;

<u>400</u> J work is done BY the engine.

The internal energy of the gas is <u>620</u> J.

6 0

2 years ago

An electrical heater 100 mm long and 5 mm in diameter is inserted into a hole drilled normal to the surface of a large block of

slega [8]

Answer:

$T_{1}=94.9^{o}C$

Explanation:

Given data

length=100mm

Diameter=5mm

Thermal conductivity=5 W/m.K

Power=50 W

Temperature=25°C

The temperature of heater surface follows from the rate equation written as:

$T_{1}=T_{2}+\frac{q}{kS}$

Where S can be estimated from the conduction shape factor for a vertical cylinder in semi infinite medium

$S=\frac{2\pi L}{ln(\frac{4L}{D} )} \\$

Substitute the given values

$S=\frac{2\pi (0.1m)}{ln[\frac{4*0.1m}{0.005m} ]}\\ S=0.143m$

The temperature of heater is then:

$T_{1}=25^{o}C+\frac{50W}{5W/m.K*0.143m} \\T_{1}=94.9^{o}C$

The temperature reached by the heater when dissipating 50 W with the surface of the block at a temperature of 25°C.

$T_{1}=94.9^{o}C$

5 0

2 years ago