Which of the following terminating decimals is equivalent to StartFraction 3 over 8 EndFraction?

Given the position vector of the particle r(t)=(t+1)i+(t^2−1)j+2t k, find the particle's velocity and acceleration vectors at t=1

Can anybody me with this? ? (picture included.)

Auniform crate c with mass mc is being transported to the left by a forklift with a constant speed v1. what is the magnitude of the angular momentum of the crate about point a, that is, the point of contact between the front tire of the forklift and the ground