The displacement d (m) of a block sliding along a straight line is given by the equation d = -0.65 t + 0.21 t2, where t is the time in seconds. What is the instantaneous velocity of the block when t = 2.0 s?

Explanation:

velocity is the change in displacement of a body with respect to time. Given the displacement d (m) of a block sliding along a straight line is given by the equation d = -0.65 t + 0.21 t², where t is the time in seconds, instantaneous velocity is expressed by differentiating the displacement with respect to time

Velocity = dd/dt

Velocity = -0.65 + 2(0.21)t²⁻¹

Velocity = -0.65 + 0.42t

The instantaneous velocity of the block when t = 2.0 s can be gotten by substituting t = 2.0s into the expression above:

Velocity = -0.65 + 0.42(2)

Velocity = -0.65 + 0.84

Velocity = 0.19

Hence the instantaneous velocity of the block when t = 2.0 s is 0.19m/s

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i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.