2. SPUTNIK: spaceflight era begins
October 4, 1957
184-pound basketball-size satellite
Lasted 3 months

3. R-7 launcher: world’s first intercontinental ballistic missile
November 3, 1957: Sputnik 2, 1120 pounds
Laika
May 15, 1958: Sputnik 3, 1.5 tons
Total mass: 367 tons
Payload: about 1 ton
Thrust: 3.9x106 N
January 15, 1958: Explorer 1 launched (US)

4. February 20, 1962
John Glenn
April 12, 1961
Yuri Gagarin

5. Robotic missions to all planets
Early timeline
April 12, 1961: the first human in space (Yuri Gagarin)
February 20, 1962: the first American on orbit (John Glenn)
1963: the first woman in space (Tereshkova)
1965: the first spacewalk (Leonov)
1969: first men on the moon (Collins, Armstrong, Aldrin)
1971: first space station (Salyut)
1981: first space shuttle flight (Columbia)
Robotic missions to all planets

6. Fathers of space programs
Wernher von Braun
Sergei Korolyov

7. Further reading: http://astronauticsnow.com/

8. M
A person is pulling a crate of mass M along the floor with a constant force F over a distance d. The coefficient of friction is .
Find the work done by the force F on the crate.
Same if F changes as F0(1+x2/d2).
Find the work done by the force of friction on the crate.
Find the net work done on the crate if the crate is pulled with a constant velocity.
Find the final velocity of the crate if the crate is pulled with a constant acceleration starting from the rest.

9. A person carries a bag of groceries of mass M with a constant velocity at the same height from the ground. Find the work done by a person on a bag.
What if a person drops the bag to the floor from height 1 m with a constant velocity? With a constant acceleration a?

10. Find the work done by a person on a backpack if
A person ascends with a constant speed;
(his velocity drops from 3 m/s at the bottom to 0.5 m/s at the top

12. Problem 5
How many joules of energy does 100 watt light bulb use per hour? How fast would a 70-kg person have to run to have that amount of energy?