When a person bends an arm a different muscle is used to bring it back to the original position. why can't the same muscle be used to both bend and unbend the arm?

A ball is thrown straight up with a speed of 3/frac{m}{s}, and it hits the ground with a speed of 15/frac{m}{s}. How tall is the tower? Ignore air resistance, and answer in meters.

The gravitational acceleration on Earth is 9.8 m/s2. A small marble is dropped to the floor, assume that as the marble falls, the only force exerted on the marble is the force of gravity (there is no air resistance).

Before you leave for a trip, you should check

In which era did the universe's clouds start to condense and the universe became transparent for the first time?

When choosing a protein it is best to choose one for high in saturated fats true or false

When the current in a toroidal solenoid is changing at a rate of 0.0270 A/s, the magnitude of the induced emf is 12.5 mV. When the current equals 1.30 A, the average flux through each turn of the solenoid is 0.00245 Wb.

A spring tide can occur at what day and month?

For a given launch velocity, at which launch angle does the projectile undergo the maximum horizontal displacement

Electric force is blank proportional to the amount of charge and blank proportional to the square of the distance between the charges

What happens in the gray zone between solid and liquid?