Two particles have positions at time t given by s1 = 4t-t^2 and s2 = 5t^2-t^3. Find the velocities at v1 and v2 at the instant the accelerations of the two particles are equal.

Animals respond in various ways to stimuli detected through their senses. some of these responses are stimulated by the presence of danger. which of these animal responses is the best example of a response to an immediate threat? a) a rooster crows every morning at the first sign of light. b) as something approaches an octopus, it shoots a cloud of ink. c) from late fall until spring, bears hibernate to preserve energy. reactivate d) a dog is getting hot in the sunlight, so he moves to a shaded area.

Acar of mass m goes around a banked curve of radius r with speed v. if the road is frictionless due to ice, the car can still negotiate the curve if the horizontal component of the normal force on the car from the road is equal in magnitude to 101) a) mv2/r b) mg/2. d) mg e) tan[v2/(eg)]

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?