Chapter 3 Flashcards
A 1-N weight has a KE of 1 J when its speed is
4.4 m/s
A 1-N weight has a PE relative to the ground of 1 J when it is at a height of
1 m
A 100-kg astronaut ejects 1 g of gas from her propulsion pistol at a speed of 50 m/s. Her recoil speed is
0.5 mm/s
A person requires about 6 million J of energy per day. This rate of energy consumption is equivalent to about
70 W
An 800-kg car moving at 80 km/h overtakes a 1200-kg car moving at 40 km/h in the same direction. If the two cars stick together, the wreckage has an initial speed of
56 km/h
An object that falls twice as far will be moving twice as fast when it hits the ground.
False
Energy is not conserved when a moving object slows to a stop.
False
Nearly all of the energy consumed today is provided by petroleum, coal, hydropower and nuclear sources.
True
Plants convert radiant energy from the Sun into chemical energy by a process called photosynthesis.
True
The energy an object has because of its position is called potential energy.
True
The increase in potential energy caused by lifting an object can be calculated by multiplying its weight by its change in height.
True
The linear momentum of a 400-kg giraffe galloping at 5 m/s is
2000 kg m/s
The watt is a unit of
power
The work done in lifting 30 kg of bricks to a height of 20 m on a building under construction is
5880 J
What never changes when two or more objects collide is
the total momentum of all the objects
When the speed of a moving object is halved,
its momentum is halved
Which of the following is not a unit of work?
Kilogram-meter
Work is the rate at which you expend energy.
False
You do more work on yourself when you run up the stairs than when you walk slowly.
False
Your electric bill for 1500 kilowatt-hours is a charge for the power you have used that month.
False
