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2 years ago

A tennis ball is hit into the air with a racket. When is the balls kinetic energy the greatest?

Physics

1 answer:

madam [21]2 years ago

3 0

Answer:

Kinetic energy is maximum when the player hits the ball.

Explanation:

Kinetic energy $=\frac{1}{2} mv^2$ , where m is the mass and v is the velocity.

So kinetic energy is proportional to square of velocity.

Velocity is maximum when the player hits the ball.

So kinetic energy is maximum when the player hits the ball.

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Which of Newton's laws explains why your hands get red when you press them hard against a wall? A. Newton's law of gravity B. Ne

Talja [164]

The ball and the wall experience the same force.

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3 years ago

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Transverse waves are sent along a 4.50 m long string with a speed of 85.00 m/s. The string is under a tension of 20.00 N. What i

frutty [35]

Answer:

m = 0.0125 kg

Explanation:

Let us apply the formula for the speed of a wave on a string that is under tension:

$v = \sqrt{\frac{F}{\mu} }$

where F = tension force

μ = mass per unit length

Mass per unit length is given as:

μ = m / l

where m = mass of the string

l = length of the string

This implies that:

$v = \sqrt{\frac{F}{m/l} }\\ \\v = \sqrt{\frac{F * l}{m} }$

Let us make mass, m, the subject of the formula:

$v^2 = \frac{F * l}{m}\\\\m = \frac{F * l}{v^2}$

From the question:

F = 20 N

l = 4.50 m

v = 85 m/s

Therefore:

$m = \frac{20 * 4.5}{85^2}\\\\m = \frac{90}{7225}\\ \\m = 0.0125 kg$

5 0

3 years ago

Heat rash is caused by chemical exposure Truth or false

Harrizon [31]

Answer:

This is false.

Explanation:

Heat rash develops when some of your sweat ducts clog. Instead of evaporating, perspiration gets trapped beneath the skin, causing inflammation and rash. Heat rash is usually self-limited, meaning it resolves on its own without treatment. Over-the-counter treatments such as calamine, hydrocortisone cream, itch preparations (such as Benadryl spray), or sunburn lotions can be used as skincare to treat the itching and burning symptoms. Heat rash usually goes away on its own within three or four days so long as you don't irritate the site further. Heat rash happens when the sweat glands get blocked. The trapped sweat irritates the skin and leads to small bumps.

3 0

2 years ago

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What is a centripetal acceleration of a point on a bicycle wheel of a radius of 0.70 m when a bike is moving 8.0 m/s

Furkat [3]

Answer:

The acceleration of a point on the wheel is 11.43 m/s² acting radially inward.

Explanation:

The centripetal acceleration acts on a body when it is performing a circular motion.

Here, a point on the bicycle is performing circular motion as the rotation of the wheel produces a circular motion.

The centripetal acceleration of a point moving with a velocity $v$ and at a distance of $r$ from the axis of rotation is given as:

$a=\frac{v^2}{r}$

Here, $v=8\ m/s,r=0.70\ m$

∴ $a=\frac{8}{0.70}=11.43\ m/s^2$

Therefore, the acceleration of a point on the wheel is 11.43 m/s² acting radially inward.

3 0

3 years ago

Newton's first law of motion states that an object will keep a constant speed and direction unless acted upon by an unbalanced f

trasher [3.6K]

Answer:

The unbalanced force that caused the ball to stop was friction

Explanation:

As Newton's second law states, the acceleration of an object is proportional to the net force applied on the object:

$F=ma$

therefore, in order to move at constant speed, an object should have a net force of zero (balanced forces) acting on it.

In this case, the ball slows down and eventually comes to a stop: it means that the ball is decelerating, so there are unbalanced forces (net force different from zero) acting on it. The unbalanced force acting on the ball is the friction: friction is a force against the motion of the object, which is due to the contact between the surface of the ball and the surface of the street, and this force is responsible for slowing down the ball.

3 0

3 years ago

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