Download presentation

1
**Kinetic energy – work theorem**

Positive net work? Kinetic energy increases. negative net work? Kinetic energy decreases. Zero net work? Constant speed.

2
**Average driving force of the biker?**

A 90.0-kg biker (bike and person) approaches a 10-% hill at a speed of 10.0 m/s. After 60.0 m uphill, his speed is 4.00 m/s. Neglect friction. Work of gravity? Work of biker? Average driving force of the biker? L17sp09

3
**A 50. 0-kg child drops off a ladder onto a thick spring mattress**

A 50.0-kg child drops off a ladder onto a thick spring mattress. The top of the ladder is 2.50 m above the surface of the mattress. If the mattress springs have an effective force constant of 50 kN/m, what is the maximum depression of the mattress?

4
A particle starts from rest at x = 0 and moves to x = L under the action of a variable force F(x), which is shown in the figure. What is the particle's kinetic energy at x=L/2 and at x=L? a) Fmax L/2, FmaxL b) Fmax L/4, 0 c) Fmax L, 0 d) Fmax L/4, Fmax L/2 e) Fmax L/2, Fmax L/4

5
Two marbles, one twice as heavy as the other, are dropped to the ground from the roof of a building. Gravity is doing work on them. Just before hitting the ground, the heavier marble has as much kinetic energy as the lighter one. twice as much kinetic energy as the lighter one. half as much kinetic energy as the lighter one. four times as much kinetic energy as the lighter one. impossible to determine

6
Power Rate of work output Constant force:

7
**Example for Power calculations**

A car is accelerating from 0 to 100 km/h in the time of 10 seconds. The mass of the car is 1000 kg. Assuming constant acceleration, determine the average power of the car engine the power the car engine has to expand at the end of the time interval.

8
**A sports car accelerates from zero to 30 mph in 1.5 s.**

How long does it take for it to accelerate from zero to 60 mph, assuming the power of the engine to be independent of velocity and neglecting friction? 2 sec 3 sec 4.5 sec 6 sec 9 sec 12 sec

9
**Work of gravity Final position Final position Final position**

Initial position Final position Initial position Final position Initial position Final position

10
**Work of gravity Work is not dependent on path**

Initial position Final position Initial position Final position Initial position Final position Work is not dependent on path Work is only dependent on initial and final position

11
**Conservative Force The force of gravity is a conservative force.**

The work of a conservative force is not dependent on path only dependent on initial and final position The force of gravity is a conservative force.

12
**Examples for non-conservative forces**

Initial position Final position Initial position Final position Friction force Applied force of pushing or pulling Initial position Final position Initial position Final position

13
**Which of the following are conservative forces? Justify answer.**

Friction Gravity close to the surface of the earth Force of the engine of a snow mobile Force exerted by a horizontal spring on a mass Drag force on a parachute at terminal velocity Gravity far away Normal force

Similar presentations

Presentation is loading. Please wait....

OK

Work and Energy.

Work and Energy.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on cse related topics about economics Ppt on spinal muscular atrophy Ppt on conservation agriculture in india Free ppt on personality development presentation Ppt on complex numbers class 11th physics Ppt on 2d viewing pipeline Ppt on employee motivation Ppt on art and architecture of delhi sultanate Ppt on positive thinking Ppt on relations and functions for class 11th sample