Forces and Newton's Laws
Newton's 1st law of motion is also known as this
Law of Inertia
Centripetal Force and Centripetal Acceleration always point how?
Towards the center of the circle
If an object does not move, is any work done?
No work is done because there is no displacement
When is the gravitational potential energy of a roller coaster the greatest?
At the top of the highest hill
What is the definition of momentum?
Mass in motion
A 10 kg desk is pushed across a classroom with an acceleration of 2.5 m/s2. What is the net force acting on the desk?
25 N
What is the momentum of a 16 kg person moving at 20m/s?
320 kg*m/s
A 2000N bear climbs a 20m tree. How much work is done by the bear?
40,000 J
What does the law of conservation of energy state?
What is the net force acting on an object that has 15 N going to the right and 7 N going to the left?
8 N Right
Draw a graph that shows the relationship between gravitational attraction and mass
Is there ever a situation where a bicycle can have more momentum than a semi-truck? Explain.
Yes if the semi-truck is not moving
How are work and Power related?
Power is the rate at which work is completed
As kinetic energy increases, what has to happen to gravitational potential energy
it has to decrease
Which of the following concepts is related to time: the amount of power something has or the amount of energy is has
Power
If you are in space and you catch a ball, do you move? Why?
yes. Newton's 3rd law of motion
When an object is in circular motion and the net forces become 0, what happens?
the object exits circular motion
An electric motor lifts an elevator that weighs 12,000N a distance of 9.00 m in 15 seconds. What is the power of the motor?
7200 Watts
If energy is "lost" transforming from kinetic to potential energy, what type of energy does it become?
Thermal energy
Draw a graph that shows the relationship between gravitational attraction and distance
negative exponential curve
Two spheres of equal masses are separated by some distance. According to Newton's Universal Law of Gravity, if you double the mass of both spheres, how does the gravitational force between them change?
quadruples
What does the law of conservation of momentum state?
The total momentum before a collision has to equal the total momentum after the collision
158.92 watts
What is the kinetic energy of a 30 kg person skiing down a hill at a speed of 22 m/s?
7260 J
It takes 5 minutes to heat a 1200 watt iron. How much work is done by the iron?
360000