[填空题]
A freight lift moveswxm/7 dhr vx), v9oy1q along a vertical stra j.h3mg b/yyl1ight line so that its velocity, v \mah3 mbl.1/ygj ythrm{~ms}^{-1} , after t seconds is given by v(t)=$1.5^{t}-4.9$ , for $0 \leq t \leq 6$ .
1. Find when the lift is at rest.
t= s.
2. Find the acceleration of the lift when t=3 .
a(3)= ms${-2}$
3. Find the total distance travelled by the lift.
d= m.
