Light rays strike a reflecting surface. They are then reflected back. You can predict the angle of the reflected light. Imagine a ball bouncing off a surface. Light can do the same thing. That is, assuming the surface is shiny. So how do you know where light will go after it strikes a shiny surface? It depends on how the light initially strikes the shiny object. Light does not always go straight toward a surface. Therefore, not all light bounces straight back. Sometimes, light can hit a surface at an angle. The angle at which it strikes the surface tells us how it will bounce off. While light is different to a ball, they react in a similar manner. Many sports rely on knowledge of reflection. Pool players know a lot about reflection. They take great care when they strike the pool ball. They need it to go to a certain place. They know the angle it will hit the side of the pool table.

What can bounce off a surface similar to a ball?

If you have a mass of 50 kg on Earth, what is your weight in newtons? An object with more mass is pulled by gravity with greater force. Mass and weight are closely related. However, the weight of an object can change if the force of gravity changes. On Earth, the force of gravity is the same everywhere. So how does the force of gravity change? It doesnt if you stay on Earth. What if we travel to another planet or moon in our solar system? Look at the photo of astronaut Edwin E. Aldrin Jr. taken by fellow astronaut Neil Armstrong in the Figure. They were the first humans to walk on the moon. An astronaut weighs less on the moon than he would on Earth. This is because the moons gravity is weaker than Earths. The astronauts mass, on the other hand, did not change. He still contained the same amount of matter on the moon as he did on Earth. If the astronaut weighed 175 pounds on Earth, he would have weighed only 29 pounds on the moon. If his mass on Earth was 80 kg, what would his mass have been on the moon? [Figure 3]

Why does an astronaut weigh less on the moon than on earth

(CNN) -- As Iranian President Mahmoud Ahmadinejad visited the U.N. General Assembly in New York last month, the spotlight was once again on Iran. And true to form, the Iranian president made his fair share of provocative statements for the Western media. But while Ahmadinejad's mercurial rants captured our media's attention, back in Iran a coordinated strategy against the women's movement continued. On the eve of Ahmadinejad's arrival to New York, Shiva Nazar Ahari, a prominent young female defender of human rights, received a heavy sentence of six years in prison on charges including the vague crime of "waging war against God" -- a convenient catch-all offense for anyone who criticizes the regime and its human rights record. There's no denying it -- Iran's women have had a bad year. Nazar Ahari joins a steadily increasing number of other women's rights activists who are in prison for no greater crime than their attempt to fight for the rights of the women. Hengameh Shahidi, Alieh Eghdam Doust, Bahareh Hedayat and Mahdiyeh Golrou have all been sent to Tehran's notorious Evin Prison on trumped-up charges related to their activism. And while Nobel Peace Prize laureate Shirin Ebadi, arguably the most internationally recognized Iranian women's rights activist, remains unable to safely return to her country, the government is targeting those affiliated with her for arrest and imprisonment, including her lawyer Nasrin Sotoudeh and her former aide Jinous Sobhani. Since the 2009 disputed elections and associated government crackdown on the overall reform movement, the government has increasingly targeted women activists. The reasons behind this go well beyond the misogynist nature of Iran's religious leadership. Rather, it is more part of a deliberate and calculated strategy of the Iranian authorities to strike at the heart of the regime's greatest vulnerability -- internal legitimacy with its own people. See more CNN.com opinion articles Iran's government recognizes and fears the broader power of the women activists who have been on the front line of reform in Iran for more than a decade. One can roughly draw an analogy between the women's movement in Iran to movements of religious groups in Burma or Tibet, or the labor "solidarity" movements in the former Eastern bloc and associated labor-Roman Catholic solidarity in Poland -- all advocating initially for the freedoms of a specific group but which provoked government fears for their transformative power to promote broader human rights progress. While the outside world occasionally reacts to the most egregious manifestations of Iran's repression of women -- such as the international condemnation associated with Sakineh Mohammadi Ashtiani, an Iranian widow sentenced to stoning on charges of alleged adultery -- these events are often portrayed simply as a consequence of the regime's archaic viewpoint about gender.
What are the names of five women who went to prison for no greater crime than their attempt to fight for the rights of women?