Answer
(a) x = 3.12 m
v = 3.12 m/s
(b) x = 21.9 m
v = 6.24 m/s
Work Step by Step
(a) We can find the acceleration of the puck.
$F = ma$
$a = \frac{F}{m} = \frac{0.250~N}{0.160~kg} = 1.56~m/s^2$
At t = 2.00 s:
$x = \frac{1}{2}at^2 = \frac{1}{2}(1.56~m/s^2)(2.00~s)^2$
$x = 3.12~m$
$v = at = (1.56~m/s^2)(2.00~s) = 3.12~m/s$
(b) At t = 5.00 s:
$x = 3.12~m + (3.12~m/s)(3.00~s) = 12.5~m$
$v = 3.12~m/s$
At t = 7.00 s:
$x = 12.5~m + (3.12~m/s)(2.00~s)+ \frac{1}{2}(1.56~m/s^2)(2.00~s)^2$
$x = 21.9~m$
$v = 3.12~m/s+(1.56~m/s^2)(2.00~s) = 6.24~m/s$
