SPUTNIK: spaceflight era begins

October 4, 1957

184-pound basketball-size satellite

Lasted 3 months

R-7 launcher: world’s first intercontinental ballistic missile

Total mass: 367 tonsPayload: about 1 tonThrust: 3.9x106 N

November 3, 1957: Sputnik 2, 1120 pounds

Laika

May 15, 1958: Sputnik 3, 1.5 tons

January 15, 1958: Explorer 1 launched (US)

April 12, 1961Yuri Gagarin

February 20, 1962John Glenn

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

Sergei Korolyov1907-1966

Fathers of space programs

Wernher von Braun1912-1977

Further reading:

• http://astronauticsnow.com/

• http://arc.iki.rssi.ru/solar/eng/history.htm

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 .

(a) Find the work done by the force F on the crate.(b) Same if F changes as F0(1+x2/d2). (c) Find the work done by the force of friction on the crate. (d) Find the net work done on the crate if the crate is pulled with a

constant velocity. (e) Find the final velocity of the crate if the crate is pulled with a constant

acceleration starting from the rest.

M

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?

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

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?