in kg⋅m2/s. This implies the particle is moving clockwise (as observed by someone on the +zaxis) for t> 0. (b) The torque is caused by the (net) force GGFma=where 2ˆ(12i)m/s.dvatdt==−GGThe remark above that only the ycomponent of Grstill applies, since ay= 0. We use GGGGGτ=× =×rFmrabgand obtain ()()()ˆˆ2.02.012k48 k N m.tt=−−−=−⋅GThe torque on the particle (as observed by someone on the +zaxis) is clockwise, causing the particle motion (which was clockwise to begin with) to increase. (c) We replace Grwith G′r(measured relative to the new reference point) and note (again) that only its ycomponent matters in these calculations. Thus, with y′= –2.0 – (–3.0) = 1.0 m, we find ()()2222.01.06.0k (12k) kg m /s.′=−−=⋅GA.The fact that this is positive implies that the particle is moving counterclockwise relative to the new reference point. (d) Using GGGGG′ =′×=′ ×rFm, we obtain ()2.01.0
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