Question on mechanics?

Tones66 · 16-07-2009, 18:42

Hi. I couldn't do this question. If anyone fancies themselves could you post your solution.Any help will be appreciated. I'm stuck. Thanks.

An unplanned impact has occurred between vehicle A and a stationary vehicle B. Markings on the road indicate that after the impact B slid a distance of 2m before coming to rest. The coefficient of kinetic friction between B's tyres and the road is 0.7 and laboratory tests indicate that a coefficient of restitution e=0.4 is appropriate for this type of impact. Mass vehicle A = 1100kg. Mass vehicle B = 1300kg.

(a) Assuming that only single impact occurred, determine whether vehicle A was exceeding the relevant speed limit of 30 km/h before the impact.(15 marks)

(b) Determine the change in momentum for vehicle B. I the duration of the impact is estimated to be 0.01 s,estimate the average force exerted on B by A during impact.(5 marks)

(c)Determine the percentage of mechanical energy lost in the impact and briefly discuss possible explanations for the energy loss.(5 marks)

**Professor_Fink** · 16-07-2009, 23:10

Yes, I could do this for you but I won't. Why don't you tell us where you run into difficulty? Then I would be happy to give you pointers, but you won't learn anything if I simply do it for you.

16-07-2009, 18:42	#1
Tones66 Registered User Join Date: Jan 2008 Location: Galway/Limerick Posts: 21 Adverts \| Friends	Question on mechanics? Hi. I couldn't do this question. If anyone fancies themselves could you post your solution.Any help will be appreciated. I'm stuck. Thanks. An unplanned impact has occurred between vehicle A and a stationary vehicle B. Markings on the road indicate that after the impact B slid a distance of 2m before coming to rest. The coefficient of kinetic friction between B's tyres and the road is 0.7 and laboratory tests indicate that a coefficient of restitution e=0.4 is appropriate for this type of impact. Mass vehicle A = 1100kg. Mass vehicle B = 1300kg. (a) Assuming that only single impact occurred, determine whether vehicle A was exceeding the relevant speed limit of 30 km/h before the impact.(15 marks) (b) Determine the change in momentum for vehicle B. I the duration of the impact is estimated to be 0.01 s,estimate the average force exerted on B by A during impact.(5 marks) (c)Determine the percentage of mechanical energy lost in the impact and briefly discuss possible explanations for the energy loss.(5 marks)

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16-07-2009, 23:10	#2
Professor_Fink Moderator Join Date: Feb 2005 Location: Oxford Posts: 709 Adverts \| Friends Mod: Physics & Chemistry	Yes, I could do this for you but I won't. Why don't you tell us where you run into difficulty? Then I would be happy to give you pointers, but you won't learn anything if I simply do it for you.