It's about 30,000 times as heavy as a Baseball
In other words, 4,000 kilograms is 27,530.89713138 times the weight of a Baseball, and the weight of a Baseball is 0.000036322826503906 times that amount.(MLB rules)
Per Major League Baseball rules, a baseball must weigh between 0.1417476156250 kilograms and 0.148834996406250 kilograms. A major league pitcher can throw a baseball at up to 150 kph (91 mph) (with a fastball pitch), with record-setting pitches as fast as 171 kph (106 mph).
It's about one-thirty-thousandth as heavy as The CN Tower
In other words, 4,000 kilograms is 0.000033924 times the weight of The CN Tower, and the weight of The CN Tower is 29,478 times that amount.(a.k.a. La Tour CN, a.k.a. Canadian National Tower, a.k.a. Canada's National Tower) (Toronto, Canada)
The CN Tower weighs approximately 117,910,000 kilograms. The Tower is home to the world's highest glass floor — a viewing area that allows visitors to look straight down 342 m (1,120 ft) to the ground below.
It's about 30,000 times as heavy as a Battery (D)
In other words, 4,000 kilograms is 29,600 times the weight of a Battery (D), and the weight of a Battery (D) is 0.0000338 times that amount.(Alkaline)
A "D" size battery weighs 0.1350 kilograms. The D size battery is the oldest of the modern battery sizes, first invented by the National Carbon Company in 1898.
It's about 45,000 times as heavy as a Deck of Cards
In other words, 4,000 kilograms is 43,000 times the weight of a Deck of Cards, and the weight of a Deck of Cards is 0.000023 times that amount.(ISO 216 B8 size, a.k.a. "poker size" 63 x 88 mm, 52-card deck)
A deck of 52 ISO 216 B8-size playing cards weighs 0.094 kilograms. Utilizing nearly 3,700 decks, the record-holding largest card tower was built in early 2010, stood over 3.5 m (11 ft), and weighed over 272 kg.
It's about one-fifty-thousandth as heavy as The Sears Tower
In other words, 4,000 kilograms is 0.00001982 times the weight of The Sears Tower, and the weight of The Sears Tower is 50,450 times that amount.(officially "Willis Tower" as of 2009) (Chicago, Illinois)
The Willis Tower weighs approximately 201,800,000 kilograms. The outer wall surface of the Tower is covered with black anodized aluminum panels which would total 110,000 sq. m (28 acres) if laid out together.
It's about 60,000 times as heavy as a Battery (C)
In other words, 4,000 kilograms is 62,000 times the weight of a Battery (C), and the weight of a Battery (C) is 0.000016 times that amount.(Alkaline)
A "C" size battery weighs 0.065 kilograms. C batteries are typically used in medium-drain devices such as musical instruments.
It's about 70,000 times as heavy as a Tennis Ball
In other words, 4,000 kilograms is 69,300 times the weight of a Tennis Ball, and the weight of a Tennis Ball is 0.0000144 times that amount.(ITF Standard; for Type 2 ball)
Per International Tennis Federation standard, regulation tennis balls must weigh about 0.0577 kilograms. Competition balls are also tested for bounce height, with the standards requiring that a ball dropped from 254 cm must bounce back to a height of 135 cm to 147 cm.