1 / 6

Impulse

Impulse. Principles of Physics. Impulse . Forces cause acceleration Acceleration is a change in velocity with respect to time Change in velocity results in a change in momentum. F net = net force (N) m = mass (kg) ( v f – v i ) = change in velocity (m/s) t = time (s).

evelia
Download Presentation

Impulse

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Impulse Principles of Physics

  2. Impulse • Forces cause acceleration • Acceleration is a change in velocity with respect to time • Change in velocity results in a change in momentum

  3. Fnet = net force (N) m = mass (kg) (vf – vi) = change in velocity (m/s) t = time (s) Newton’s 2nd Law Fnet = ma Fnet = m(vf – vi) t Fnett = m(vf– vi) impulse change in (Ns) momentum (kg m/s) 1Ns = 1 kg m/s

  4. When is impulse important?? Car crashes By increasing the time of the collision the force felt by the passengers is reduced. Airbags cushion the impact (allow impact to take longer) Ft = m(vf – vi) Why would it be better to hit a hay stack instead of a brick wall? What do catchers allow their arms to move backwards when they catch?

  5. Example A hockey player takes a slap shot, exerting a force of 30 N on a hockey puck for 0.16 s. If the puck had a mass of 0.115 kg and started from rest, what speed does it have as it heads towards the net? Givens: F =30 N t = 0.16 s m = 0.115 kg vi = 0 Ft = m(vf – vi) (30)(0.16 ) = 0.115(vf– 0) vf= 41.8 m/s

  6. Example Small rockets are used to make small adjustments in speed of satellites. One such rocket has a thrust of 35 N. If it is fired to change velocity of a 72,000 kg spacecraft by 0.63 m/s, how long should it be fired? Givens: F =35 N t = ? m = 72,000 kg (vf – vi)= 0.63 m/s Ft = m(vf – vi) (35)(t) = 72,000(0.63) t = 1,296 s = 21.6 min

More Related