A pendulum consists of a mass of 10 kg attached to a rigid massless rod of length 2m. If the mass is doubled to 20 kg, what happens to the period of the pendulum?  

An object is moving on a circular path of radius π meters at a constant speed of 4.0m/s. The time required for one revolution is:

A 3 kg box sits on a spring (k = 100 N/m), which is secured to the floor of a rocket deep in space (far from any gravitational force). The rocket is accelerating forward with an acceleration of 2 m/s2. What is the compression (

An object is in a region such that its system’s potential energy as a function of position is as graphed below. What is the y component of the conservative force associated with the potential energy at y = 18 m?

A 2 kg mass attached to a massless spring undergoes undamped simple harmonic motion, with a position given by

A car of mass m is moving around a banked circular curve with a radius of R. The picture shows a cross-section of the road partway through the turn. The car is traveling out of the page. The car is traveling steadily around the curve with a constant speed and maintaining a constant radius R. There is a certain speed v0 for the car, at which there is no frictional force from the tires. What is v0?  

Translate the following sentences into English.   1.  我的哥哥喜欢绿色。 wǒ de gē ge xǐ huān lǜ sè . 2.  爷爷没有狗。yé ye méi yǒu gǒu . 3.  他会说中文。tā huì shuō zhōng wén .    

The oldest evidence for metazoan (animal) life is the preservation of sponge biomarkers in the Cryogenian. 

The “Founder” effect refers to a small group of geographically isolated individuals that fully represent the total genetic variability of their larger parent population. 

Exaptation involves the adaptive repurposing of a preexisting morphological character to serve a new function.