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dusya [7]
3 years ago
7

A father racing his son has 1/3 the kinetic energy of the son, who has 1/4 the mass of the father. The father speeds up by 1.5 m

/s and then has the same kinetic energy as the son. What are the original speeds of
(a) the father and
(b) the son?
Physics
1 answer:
Feliz [49]3 years ago
8 0

Explanation:

Let the speeds of father and son are v_f\ and\ v_s. The kinetic energies of father and son are K_f\ and\ K_s. The mass of father and son are  m_f\ and\ m_s

(a) According to given conditions, K_f=\dfrac{1}{3}K_s

And m_s=\dfrac{1}{4}m_f

Kinetic energy of father is given by :

K_f=\dfrac{1}{2}m_fv_f^2.............(1)

Kinetic energy of son is given by :

K_s=\dfrac{1}{2}m_sv_s^2...........(2)

From equation (1), (2) we get :

\dfrac{v_f^2}{v_s^2}=\dfrac{1}{12}..............(3)

If the speed of father is speed up by 1.5 m/s, so the ratio of kinetic energies is given by :

\dfrac{K_f}{K_s}=\dfrac{1/2m_f(v_f+1.5)^2}{1/2m_sv_s^2}

v_s^2=4(v_f+1.5)^2

Using equation (3) in above equation, we get :

v_f=\dfrac{1.5}{\sqrt3-1}=2.04\ m/s

(b) Put the value of v_f in equation (3) as :

v_s=7.09\ m/s

Hence, this is the required solution.

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alexgriva [62]

Answer:

Number of turns on the secondary coil of the adapter transformer is 10.

Explanation:

For a transformer,

    \frac{V_{s} }{V_{p} } = \frac{N_{s} }{N_{p} }

where V_{s} is the voltage induced in the secondary coil

           V_{p} is the voltage in the primary coil

          N_{s} is the number of turns of secondary coil

         N_{p} is the number of turns of primary coil

From the given question,

    \frac{487*10^{-3} }{120} = \frac{N_{s} }{2464}

⇒    N_{s} = \frac{2462*487*10^{-3} }{120}

            = 9.999733

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5 0
3 years ago
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A 12kg cheetah accelerates 24 m/s". What is the force the cheetah needed to run?
Kobotan [32]

Answer:

288N

Explanation:

Given parameters:

Mass of Cheetah = 12kg

Acceleration  = 24m/s²

Unknown:

Force needed by the cheetah to run  = ?

Solution:

The force needed by the Cheetah to run is the net force.

According to Newton's law;

    Force  = mass x acceleration

Insert the given parameters and solve;

   Force  = 12 x 24  = 288N

7 0
3 years ago
Please help me quickly!!!
vichka [17]
Hey! So referring to the data the thing we can clearly see is that in a vacuum, everything, regardless of its mass, falls at the same speed.

Acceleration is often confused with speed, or velocity, but the difference is, acceleration by definition is the rate of which an object falls with respect to its mass and time.

Every single thing in the world falls at the same acceleration, this is because of gravity. The difference is the speed of which it falls. In space, there is not any gravity, and so, the objects are able to fall at the same speed regardless of their mass.
6 0
3 years ago
What is the mass of a bird if it has a potential energy of 147J when flying at a height of 30 m above the ground?
Artist 52 [7]

Answer:

0.5kg

Explanation:

Given parameters:

Potential energy = 147J

Height  = 30m

Unknown:

Mass of the bird  = ?

Solution:

Potential energy is the energy due to the position of a body. Now, the expression for finding the potential energy is given as;

      P.E  = mgH

m is the mass

g is the acceleration due to gravity = 9.8m/s²

H is the height

      147  = m x 9.8 x 30

         m = 0.5kg

5 0
3 years ago
A 500 kg table with 4 legs rests on solid flat ground. I place 3 books on the center of the table with masses of 10 kg, 20 kg an
BARSIC [14]

Answer:

1,373.4 N

Explanation:

The mass of the table acts at the centre in addition to the books since that is the centre of gravity of the table.

Mass of books will be 10kg+20kg+30kg=60 kg

Total mass of table and books will be 500kg+60kg=560 kg

This mass is evenly distributed into the four legs hence 560kg/4 legs=140 kg per leg

Force is product of mass and acceleration due to gravity hence F=gm

Taking g as 9.81 m/s2 then

F=140*9.81=1,373.4 N

Therefore, rhe normal force is equivalent to 1,373.4 N

6 0
3 years ago
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