# mitx 8.01x Classical Mechanics

posted by
**youlife**
.

An object is moving along a straight line parallel to the x-axis. Its position as a function of time is given by:

x(t)=30 m−21 (ms) t+3 (ms2) t2

where the position x is in (m) and the time t is in (s).

(a) What is the object's velocity at t=0 s, 2 s, and 5 s? (enter the x-component of the velocity in m/s. Do not enter the units in the box.)

vx(t=0)=

vx(t=2)=

vx(t=5)=

(b) What is the object's acceleration at t=0 s, 2 s, and 5 s? (enter the x-component of the acceleration in m/s2. Do not enter the units in the box.)

ax(t=0)=

ax(t=2)=

ax(t=5)=

(c) At what time T is the object's velocity zero?(Enter your answer in s. Do not enter the units in the box.)

T=

What is the object's position when its velocity is zero? (Enter the x-component of the position in m. Do not enter the units in the box.)

x(T)=

(d) What is the average velocity between t1= 1.0 s and t2=3.5 s? (Enter the x-component in m/s. Do not enter the units in the box.)

v¯x,t1,t2=

(e) What is the object's average velocity between t1= 0 s and t2=7.0 s? (Enter the x-component in m/s. Do not enter the units in the box.)

v¯x,t1,t2=

(f) What is the object's average speed between t1= 0 s and t2=7.0 s? (Enter the x-component in m/s. Do not enter the units in the box.)

(g) At what time t3 does the object reverses its direction? (Enter your answer in s)

t3=