4.4.5 Work and Nonconservative Forces Flashcards
Work and Nonconservative Forces
• You can use the equation to solve problems involving external or nonconservative forces
A 2 kg block slides down an incline that is 40 m long and 10 m high. It moves at 12 m / s when it reaches the bottom of the incline. Which of the following is the force of friction between the block and the incline?
1.3N
If a 3 kg car is pushed on an air track at a constant force for 10 cm and the car ends up with a speed of 40 cm / s, how much force was applied?
2.4 N
An 80 kg paratrooper is falling at 90 m / s before he opens his chute and slows to 3 m / s. If his chute exerts a frictional force of 2,200 N, how far does he have to fall before he slows to 3 m / s?
228 m
A 2 kg block slides down an incline that is 10 m high and moves at 12 m / s when it reaches the bottom of the incline. How much work was done by friction?
52 J
How much drag force is required to stop a 5,000 kg boat moving at 6 m / s in 30 m?
3000 N
If a car weighs 1,500 kg and its engine can exert a constant maximum force of 3,750 N, how fast will the car be moving at the end of 50 m?
15.8 m / s
Consider a car weighing 1,500 kg with an engine that can exert a constant maximum force of 3,750 N. The car has moved 50 m when it reaches its maximum velocity. When the car is moving at its maximum velocity, the driver hits the brakes, which apply a decelerating force of 5,000 N. How far will the car travel before it stops?
37.5 m
Which of the following statements about conservation of energy is not true?
The total mechanical energy is always constant.
Consider a car weighing 1,500 kg containing three people weighing a total of 240 kg. The car’s engine can exert a constant maximum force of 3,750 N. How fast will the car be moving at the end of 50 m?
14.7 m / s
