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11111nata11111 [884]
3 years ago
15

"A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be po

inted upstream (that is, relative to its actual path) to go straight across the river?

Physics
1 answer:
IRISSAK [1]3 years ago
8 0

Answer:

30 degrees

Explanation:

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Suppose Tom Harmon17 is standing at the exact center of the Ohio State football field18 on the 50 yard line. The field is 300 fe
nignag [31]

Answer:

a) x = 40 t , y = 39 t ,  z = 6 + 32 t - 16 t ²,   b)     x = 80 feet ,  y = 78 feet , the ball came into the field  

Explanation:

a) This is a projectile launch exercise, where in the x and y axes there is no acceleration and in the z axis the acceleration of the acceleration of gravity, let's write the equations of motion in each axis

Since the cast is in the center of the field, let's place the coordinate system

          x₀ = 0

          y₀ = 0

          z₀ = 6 feet

x-axis (towards end zone,  GOAL zone)

         x = xo + v₀ₓ t

        x = 40 t

y-axis (field width)

        y = y₀ + v_{oy} t

        y = 39 t

z axis (vertical)

        z = z₀ + v_{oz} t - ½ g t²

        z = 6 + 32 t - ½ 32 t²

        z = 6 + 32 t - 16 t ²

b) The player catches the ball at the same height as it came out, so we can find the time it takes to arrive

          z = 6

          6 = 6 + 32 t - 16 t²

          (t - 2)t  = 0

           t=0 s

           t= 2 s

The ball position

          x = 40 2

          x = 80 feet

           

          y = 39 2

          y = 78 feet

the dimensions of the field from the coordinate system (center of the field) are

             x_total = 150 feet

             y _total = 80 feet

so we can see that the ball came into the field

6 0
3 years ago
A 30.0 g mass of iron at 24.5°C is heated to 45.0°C. The theoretical specific
diamong [38]

Answer:

276.135 J

Explanation:

Given that:

mass of Fe = 30.0 g

initial temperature = 24.5°C

final temperature = 45.0°C

specific heat of Fe = 0.449 J/g°C

We can determine the thermal energy added by using the formula;

Q = mcΔT

Q = 30.0g × 0.449 J/g°C × (45.0 - 24.5)°C

Q = 276.135 J

8 0
3 years ago
Explain the following defects of a simple electric cell:
eimsori [14]

Answer:

Explanation:

The two major defects of simple electric cells causes current supplied to be for short time. These defects are: polarization and local action.

a. Polarization: This is a defect caused by an accumulation of hydrogen bubbles at the positive electrode of the cell. It can be prevented by the use of vent, using a hydrogen absorbing material or the use of a depolarizer.

b. Local Action: This is the gradual wearing away of the electrode due to impurities in the zinc plate. It can be controlled by the amalgamation of the zinc plate before it is used.

4 0
3 years ago
What’s the answer for this problem?
pickupchik [31]
The answer is always true a



4 0
3 years ago
3.1
Ilia_Sergeevich [38]

Answer:

The value is  C = 30729\  c

Explanation:

From the question we are told that

  The power rating of the stove is  P = 4.4 KW  = 4.4 *10^{3} \  W

   The duration of its use everyday is t_1  = 70 \ minutes  = 1.167 \ hours    

    The rating of the light bulbs is P_2'  = 150 W

   The number is n = 7

   The power rating of the total  bulb is  P_2 = 7 * 150 = 1050 \  W

    The duration of its use everyday is  t_2  = 7 hours

    The power rating of miscellaneous appliance P_3 = 1.8 \ KW = 1.8 *10^{3} \  W

    The duration of its use everyday is t_3 = 1 hour

     The power rating of hot water P = 4 KW  = 4 *10^{3} \  W

      The duration of its use everyday is t_4 = 120 \ minutes  = 2 hours

Generally the total electrical energy used in 1 month is mathematically represented as

    E = P_1 * t_1 * 30 + P_2 * t_2 * 30 + P_3 * t_3 * 30+ P_4 * t_4 * 30

=>  E = 4.4*10^{3} * 1.167  * 30 + 1050 * 7 * 30 + 1.8 *1 * 30+ 4*10^{3} * 2 * 30

=>  E = 614598  \ W \cdot h

=>   E = 614.6  \  K W \cdot h

Generally the monthly electricity  bill is mathematically represented as

    C = 614.6 * 50

=> C = 30729\  c

8 0
3 years ago
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