A student measures the speed of a rolling ball three times. She adds the measurements and divides by 3. What quantity did the student calculate?

Humans protect themselves from natural disasters by all of the following except dams sunscreen building homes/shelters levees

A rope and pulley system is used to lift a box that weighs 90 Newton's. How much force do you need to pull on the rope if the machine has a mechanical advantage of 5?

A 30.0 kg dolphin decelerates from 12.0 to 7.00 m/s in 2.60 s to join another dolphin in play. What average force (in N) was exerted to slow him if he was moving horizontally? (The gravitational force is balanced by the buoyant force of the water.

Explain, in terms of their structure and bonding, why the element Sulphur is a non-conductor of electricity and aluminium is a good conductor of electricity.

Why would scientists use a control sample that has no dna from bighead carp in edna surveillance? a. to amplify the dna in small samples b. to serve as a positive control against samples c. to cut sample dna into fragments d.

Two masses are separated by 1 m. suppose the masses are moved so they are 2 m apart how will the gravitational force change

Bob rubs a piece of fur on a hand rubber rod, giving the rod a negative charge. what happens?

The period of a simple pendulum is 3.8 s. the length of the pendulum is doubled. what is the period t of the longer pendulum? t = s

True or false - sound waves can travel across outer space.

In which one of the following locations can a person hear the echo of a sound? a. At least 33.2 meters behind the reflecting surface b. Less than 16.6 meters in front of the reflecting surface c. Less than 33.2 meters behind the reflecting surface d.