# Can someone explain to me: Number 4 Number 7 Number 8 in the midterm review packet

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• You are told that the charge of an electron, e, has dimensions [Q], and that a volt, V , has dimensions [M][L2 ] [Q][T] 2 , the speed of light has dimensions [L]/[T], and momentum has dimensions of [M][L]/[T]. Use dimensional analysis to determine how to express the momentum in terms of e, V , and c. Henry commented over 1 year ago
• A certain object is accelerating at a = αt for times larger than zero. Find the velocity as a function of time. Henry commented over 1 year ago
• https://imgur.com/a/9zL8s Henry commented over 1 year ago
• Hmm, could you double check the given dimensions of voltage for the first question? Juan commented over 1 year ago
• If a=αt, then a(t)=αt. Since, velocity is the integral of acceleration, v(t)=∫a(t)=α∫t=1/2αt^2 Juan commented over 1 year ago
• 7) deltay=Voyt+1/2at^2. Voy=0 so deltay=1/2(-9.81)(1.21^2)=-7.17 m Juan commented over 1 year ago
• 8) tanθ=y/x, θ=tan^-1(y/x). So θ=tan^-1(-7.17/19.36)=-20.32° Juan commented over 1 year ago