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alukav5142 [94]
1 year ago
13

Josie ran at an average speed of 16 m/s. if her mass 10 kg, what was her kinetic energy as she crosses her finish line?

Physics
2 answers:
levacccp [35]1 year ago
4 0

I have to be honest with you . . . It's not possible to determine the answer with only the information given in the question.

Kinetic energy = (1/2) (mass) (speed squared).

Josie's Kinetic energy as she crosses the finish line is

(1/2) (her mass) (her speed as she crosses the finish line)².

That's (5 kg) x (her speed as she crosses the finish line)² .

But read the question again.

WE DON'T know her speed as she crosses the finish line.

The question only tells us her average speed for the whole race.

We can be confident that her <u><em>Average</em></u> Kinetic Energy was

(5 kg) (16 m/s)²  =  1,280 Joules.

But we can't tell what her kinetic energy was as she crossed the finish line, beause we don't know what her speed was at that instant.

Helen [10]1 year ago
3 0

Answer: 1280 J

KE=\frac{1}{2}mv^{2}  \\\\KE= \frac{1}{2} (10 kg)(16 m/s)^2\\=1280 J

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expain why different atoms of the same element always have the same atomic number but can have different mass numbers what are t
anzhelika [568]
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4 0
2 years ago
A metal rod has a moves with a constant velocity of 40 cm/s along two parallel metal rails through a magnetic field of 0.575 T.
love history [14]

Answer:

2.12/R mW

Explanation:

The electrical power, P generated by the rod is

P = B²L²v²/R where B = magnetic field = 0.575 T, L = length of metal rod = separation of metal rails = 20 cm = 0.2 m, v = velocity of metal rod = 40 cm/s = 0.4 m/s and R = resistance of rod = ?

So, the induced emf on the conductor is

E = BLv

= 0.575 T × 0.2 m × 0.4 m/s

= 0.046 V

= 46 mV

The electrical power, P generated by the rod is

P = B²L²v²/R

=  B²L²v²/R

So, P = (0.575 T)² × (0.2 m)² × (0.4 m/s)²

= 0.002116/R W

= 2.12/R mW

3 0
3 years ago
.1 An 8-ft 3 tank contains air at an initial temperature of 808F and initial pressure of 100 lbf/in. 2 The tank develops a small
Alina [70]

Correct temperature is 80°F

Answer:

T_f = 38.83°F

Explanation:

We are given;

Volume; V = 8 ft³

Initial Pressure; P_i = 100 lbf/in² = 100 × 12² lbf/ft²

Initial temperature; T_i = 80°F = 539.67 °R

Time for outlet flow; t_o = 90 s

Mass flow rate at outlet; m'_o = 0.03 lb/s

Final pressure; P_f = 30 lbf/in² = 30 × 12² lbf/ft²

Now, from ideal gas equation,

Pv = RT

Where v is initial specific volume

R is ideal gas constant = 53.33 ft.lbf/°R

Thus;

v = RT/P

v_i = 53.33 × 539.67/(100 × 12²)

v_i = 2 ft³/lb

Formula for initial mass is;

m_i = V/v_i

m_i = 8/2

m_i = 4 lb

Now change in mass is given as;

Δm = m'_o × t_o

Δm = 0.03 × 90

Δm = 2.7 lb

Now,

m_f = m_i - Δm

Thus; m_f = 4 - 2.7

m_f = 1.3 lb

Similarly in above;

v_f = V/m_f

v_f = 8/1.3

v_f = 6.154 ft³/lb

Again;

Pv = RT

Thus;

T_f = P_f•v_f/R

T_f = (30 × 12² × 6.154)/53.33

T_f = 498.5°R

Converting to °F gives;

T_f = 38.83°F

7 0
3 years ago
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