No Friction No Air resistance At Rest

Several physical situations are described below. For each situation, simplify the work-energy equation by canceling any zero terms and any energy terms (whether KE or PE) which are unchanging. Explain each term which gets canceled. A Hot Wheels car starts from rest on top of an inclined plane and rolls down the incline through a loop and along a horizontal surface. Friction and air resistance have a significant effect on the car. Simplification of Work-Energy Equation KEi + PEi + Wnc = KEf + PEf

When released, a 120-g block slides down the path shown below, reaching the bottom with a speed of 4 m/s. How much work does the force of friction do? 2.0 m 4.0 m/s Image Description W = J

Before railroads were invented, goods often traveled along canals, with mules pulling barges from the bank. If a mule is exerting a 1200 N force for 10 km, and the rope connecting the mule to the barge is at a 20 degree angle from the direction of travel, how much work did the mule do on the barge?  a. 12 MJ b. 11 MJ c. 4.1 MJ d. 6 MJ

ACTIVITY 4: DECODE THE MESSAGE Directions: Determine the work done by the force on a given system in the following problems. Then, decode the message. I hv a e 4 Displacement (m E You pull your bag with a force of 30 N parallel to the ground classroom 20 m away. How much work will you do on your bag? MA crate is being lifted into a truck. If it is moved with a 2470 N force and 3650 J of work is done, then how far is the crate being lifted? M You must exert a force of 4.5 N on a book to slide it across a table. If you do 2.7 J of work in the process, how far have you moved the book? towards your

1. A roller-coaster car with a mass of 1200 kg starts at rest from a point 20 m above the ground. At point B, it is 9 m above the ground. [Express your answers in kilojoules (kJ).] a. What is the initial potential energy of the car? b. What is the potential energy at point B? c. If the initial kinetic energy was zero and the work done against friction between the starting point and point B is 40 000 J (40 kJ), what is the kinetic energy of the car at point B 2. The time required for one complete cycle of a mass oscillating at the end of a spring is 0.80 s. What is the frequency of oscillation?

A 70.0 kg skier , starting with a speed of 1.00 m/s skies down a rough 17.0 m high ski hill and then goes up and off a ramp, as shown. a. What is the work done by friction as the skier travels down the hill from the start to the bottom of the hill? b. How high will the skier rise after leaving the bottom ramp? 2 Vo=1.0 m/s H=17.0 m V2=15.0 m/s

... question 8 please thanks../....

Question 8 This graph shows different types of energy for a roller coaster car that starts at the top of a large hill and goes down to its lowest point at 6 s. Energy of a Roller Coaster Car 500 450 400 According to the graph, what is the most likely relationship between height and potential energy? 350 3 300 S 250 200 150 100 50 10 Time (s) - Mechanical Energy ...... Potential Energy Kinetic Energy Your answer: O They are directly related. O They are inversely related. O There is no relationship between the two. O There is not enough information for a conclusion.

A coin slides over a frictionless plane and across an xy coordinate system from the origin to a point with xy coordinates (2.20 m, 4.50 m) while a constant force acts on it. The force has magnitude 2.80 N and is directed at a counterclockwise angle of 103. from the positive direction of the x axis. How much work is done by the force on the coin during the displacement? Number i Units