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irina1246 [14]
2 years ago
8

I really need help

Physics
1 answer:
Nutka1998 [239]2 years ago
5 0

Answer:

E = 12.9 kJ

Explanation:

Given that,

Mass of John, m = 55 kg

It is standing on the edge of a diving board which is at a height of 24 m.

We need to find his mechanical energy. The mechanical energy of John is equal to its potential energy such that,

E = mgh

E = 55  kg × 9.8 m/s² × 24

E = 12936  J

or

E = 12.9 kJ

So, his mechanical energy is equal to 12.9 kJ.

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How many joules of electrical energy is transferred per second by 6V 0.5 A lamp?
Degger [83]

When you ask for "joules per second", you're asking for "watts".
The rate of energy "transfer" is 'power'.  In this case, the light bulb
transfers energy out of the electrical circuit and into the space
around it, in the form of light and heat radiation.

Electrical power = (voltage) x (current) =

                              (6 volts) x (0.5 ampere) =

                                          3 watts  =  3 joules per second.
 
4 0
3 years ago
A 75-m-long train begins uniform acceleration from rest. the the train has a speed of 23 m/s when it passes a railway worker tan
Lapatulllka [165]

Answer:

acceleration a = 1.04 m/s2

Explanation:

Assume the train has a speed of 23m/s when the last car passes the railway workers. Once this happens the last car would have traveled a total distance of the 180m distance between the railway worker standing 180 m from where the front of the train started plus the 75m distance from the first car to the last car:

s = 75 + 180 = 255 m

We can use the following equation of motion to find out the distance traveled by the car:

v^2 - v_0^2 = 2aswhere v = 23 m/s is the velocity of the car when it passes the worker, v_0 = 0m/s is the initial velocity of the car when it starts, a m/s2 is the acceleration, which we are looking for.

23^2 - 0^2 = 2*a*255

510a = 529

a = 529 / 510 = 1.04 m/s^2

8 0
3 years ago
A 500kg car skids to a stop at a traffic light, leaving behind a 18.25m skid mark as it comes to a rest. Assuming that the car i
Nastasia [14]

Answer:

Coefficient of friction will be 0.587

Explanation:

We have given mass of the car m = 500 kg

Distance s = 18.25 m

Initial velocity of the car u = 14.5 m/sec

As the car finally stops so final velocity v = 0 m/sec

From second equation of motion

v^2=u^2+2as

0^2=14.5^2+2\times a\times 18.25

a=-5.76m/sec^2

We know that acceleration is given by

a=\mu g

5.76=\mu\times  9.81

\mu =0.587

So coefficient of friction will be 0.587

6 0
3 years ago
After the box comes to rest at position x1, a person starts pushing the box, giving it a speed v1. when the box reaches position
KiRa [710]

As we know by work energy theorem

total work done = change in kinetic energy

so here we can say that wok done on the box will be equal to the change in kinetic energy of the system

W_p = KE_f - KE_i

initial the box is at rest at position x = x1

so initial kinetic energy will be ZERO

at final position x = x2 final kinetic energy is given as

KE_f = \frac{1}{2}mv_1^2

now work done is given as

W_p = \frac{1}{2}mv_1^2 - 0

so we can say

W_p = \frac{1}{2}mv_1^2

so above is the work done on the box to slide it from x1 to x2

3 0
3 years ago
You drive on Interstate 10 from San Antonio to Houston, half the time at 75 km/h and the other half at 106 km/h. On the way back
r-ruslan [8.4K]

Answer:

Explanation:

a ) from San Antonio to Houston let distance be d km .

Average speed = total distance / total time

time = distance / speed

Total time = (d / 2 x 75 ) +( d / 2 x 106 )

= .0067 d + .0047 d

= .0114 d

Average speed  = d / .0114 d = 87.72 km /h

b ) from Houston back to San Antonio

Total time = (d / 2 x 106 ) +( d / 2 x 75 )

= .0047 d + .0067 d

= .0114 d

Average speed  = d / .0114 d = 87.72 km /h

c )

For entire trip :

total distance = 2d

total time = 2 x .0114 d

Average speed  = 2 d / 2 x .0114 d

= 87.72 km /h .

4 0
3 years ago
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