Why are time machines not invented?

When did games get invented

A baseball is thrown with a horizontal velocity of 40.20 m/s and no vertical velocity. If the ball leaves the pitcher's hand at a height of 2.

A falling stone is at a certain instant 90 feet above the ground. two seconds later it is only 10 feet above the ground. if it was thrown down with an initial speed of 4 feet per second, from what height was it thrown?

Electrons in an x-ray tube are accelerated through 144 kV and directed toward a target to produce x-rays. Calculate the power of the electron beam in this tube if it has a current of 16.0 mA

How much force is required to accelerate a 1,800kg truck at 3m/s/s

Which statement is correct about gasoline when it is burned? Heat energy is created by the gasoline. The total energy of the gasoline decreases. Chemical energy in the gasoline is destroyed. Chemical energy is transformed into heat energy.

The tilt of the Earth's axis of rotation changes over a period of 41,000 years. Which of these statements best predicts a long term effect of the changes in the tilt of the Earth's axis of rotation? a. The Earth's climate would change. b.

What do keratinized cells form?

Explain why Planck's introduction of quantization accounted for the properties of black-body radiation.

How and which waves travel either through a medium or a vacuum?