Một electron điện tích e, khối lượng m chuyển động đều trên một quỹ đạo tròn bán kính r quanh hạt nhân nguyên tử Hidro. Xác định vận tốc chuyển động của electron trên quỹ đạo. Cho e  1,61019 C, m  9,11028 g , khoảng cách trung bình từ electron đến hạt nhân là r  108 cm.

Asuppose a suitcase has a mass of (m) 30 kg and a net force (n) of 10 kg*m/s. what is the acceleration rate of the suitcasein m/s? show your work to support your answer.

Each neuron shown in this figure innervates a group of muscle fibers. what is the term for a group of muscle fibers innervated by a single neuron?

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?