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3 years ago

What is her initial acceleration if she is initially stationary and wearing steel-bladed skates that point in the direction of?

1 answer:

7 0

We will apply the Newton's second Law so the we will be able to find the acceleration.
F (tot) = ma
a = F(tot) / m
a = 32.0 N / 65.0 kg = 0.492 m/s^2
Approximately 0.492 m/s^2 is her initial acceleration if she is initially stationary and wearing steel-bladed skates.

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When is the angular momentum of a system constant?

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I think it’s a but I’m not 100% sure

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3 years ago

a tennis ball is hit upward with a tennis racket an initial velocity of 12 m/s. What will the ball's speed be when it returns to

zaharov [31]

Answer: 12 m/s

Explanation:

If we ignore air resistance, gravity alone will reduce the upward velocity to zero at the top of the flight. As gravity is a conservative force, it will return exactly the same amount of energy to the tennis ball when it returns to the original elevation.

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3 years ago

A 75-hp (shaft output) motor that has an efficiency of 91% is worn out and is replaced by a high efficiency 75-hp motor that has

ZanzabumX [31]

Answer:

The heat gain of the room due to higher efficiency is 2.84 kW.

Explanation:

Given that,

Output power of shaft = 75 hp

Efficiency = 91%

High efficiency = 95.4%

We need to calculate the electric input given to motor

Using formula of efficiency

$\eta=\dfrac{Work\ Output}{Work\ input}$

$Work\ Input =\dfrac{Work\ output}{\eta}$

$Work\ Input =\dfrac{75\times746}{0.91}$

$Work\ Input =61483.51\ W$

$Work\ Input = 61.48 kW$

We need to calculate the electric input

For, heigh efficiency

$Work\ Input_{inc} =\dfrac{75\times746}{0.954}$

$Work\ Input_{int} =58647.7\ W$

$Work\ Input_{int} = 58.64\ kW$

The reduction of the heat gain of the room due to higher efficiency is

$Q=Work\ Input-Work\ Input_{int}$

Put the value into the formula

$Q=61.48 -58.64$

$Q=2.84\ kW$

Hence, The heat gain of the room due to higher efficiency is 2.84 kW.

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3 years ago

Where do you find electromagnetic waves on earth? what are some everyday uses?

Norma-Jean [14]

Answer:

Radio waves are used for communications and radar. Microwaves are used to cook your food. Infrared waves are used in remote controls and are emitted from all warm objects, allowing them to be used to create heat-sensitive cameras.

Explanation:

Basically electromagnetic waves can be found in your everyday life.

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3 years ago

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What do a mirror and a magnifying glass have in common? What makes them different?

jeka57 [31]

Answer:

They both have a reflection, but a mirror just reflects anything in front of it, while a magnifying glass helps you see closer through the reflection of something.

Explanation:

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4 years ago