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3 years ago

Which runner has greater kinetic energy: a 45 kg runner moving at a speed of 7 m per second or a 93 kg runner moving at a

Physics

1 answer:

bagirrra123 [75]3 years ago

7 0

Kinetic Energy = (1/2) (mass) (speed)

First runner: KE = (1/2) (45kg) (49 m/s) = 1,102.5 Joules

Second runner: KE = (1/2) (93kg) (9 m/s) = 418.5 Joules

The <em>first runner </em><em>has 163</em>% more kinetic energy than the second runner has.

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A hockey puck is pushed by a stick with a force of 750 newton’s. the puck tracked 2.0 meters in 0.30 seconds. how powerful is th

Anit [1.1K]

Work= force x distance
work= 750 x 2
work =1500
power =work/time
power= 1500/ 0.3
power= 5000W

answer: b. 5000W

7 0

3 years ago

The speed of a tennis ball that is served is 73.14 m/s. During a serve, the ball typically starts from rest and is in contact wi

Serga [27]

Answer: Third option

F = 250w

Explanation:

The impulse can be written as the product of force for the time interval in which it is applied.

$I = F (t_2-t_1)$

You can also write impulse I as the change of the linear momentum of the ball

$I = mv_2 -mv_1$

So:

$F (t_2-t_1) = mv_2 -mv_1$

We want to find the force applied to the ball. We know that

$(t_2-t_1) = 30$ milliseconds = 0.03 seconds

The initial velocity $v_1$ is zero.

The final speed $v_2 = 73.14\ m / s$

$F * 0.03 = 73.14m$

$F * 0.03 = 73.14m\\\\F=\frac{73.14m}{0.03}\\\\F=2438m$

We must express the result of the force in terms of the weight of the ball.

We divide the expression between the acceleration of gravity

$g = 9.8\ m / s ^ 2$

$F=\frac{2438m*g}{g},\ \ m*g=w\\\\g=9.8\ m/s^2\\\\F=\frac{2438w}{9.8}\\\\F=249w$

The answer is the third option

3 0

3 years ago

Which part of this model represents a layer made of liquid rock that produces

goblinko [34]

Answer: C- the outer core

Explanation: The outer core is a thick layer of molten rock that encircles the inner core.

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3 years ago

List five different institutional sources of contracts that you know

dmitriy555 [2]

The contract of citizenship, the contract of merriage, the contract of loan, the contract of power, and the contract of health care. All these are examples of a contract on institutional level

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3 years ago

If E=1/2Av^2+Bmx find the dimensions of A and B(Where E is energy,v,m and x are velocity,mass and distance respectively)

sp2606 [1]

Answer:

A = [kg]

B = [m/s²]

Explanation:

E = ½ Av² + Bmx

Substitute the units:

[J] = ½ A [m/s]² + B [kg] [m]

A Joule written in base units is:

1 J = 1 Nm = 1 kg m²/s²

Each term must have the same units.

[kg m²/s²] = A [m/s]²

[kg m²/s²] = A [m²/s²]

A = [kg]

[kg m²/s²] = B [kg] [m]

B = [m/s²]

8 0

3 years ago