A block slides on a frictionless horizontal track with an initial speed of at

PHYSICS · Single correct · AP · Physics C: Mechanics · Work Energy and Power · Work Energy and Power

Problem

2\,\text{kg}

block slides on a frictionless horizontal track with an initial speed of

2\,\text{m\,s}^{-1}

x=0

. The horizontal force acting on it is piece-wise: • From

x=0

x=4\,\text{m}

F(x)=10-2x\,\text{N}

. • From

x=4\,\text{m}

x=7\,\text{m}

F=-4\,\text{N}

(opposite the direction of motion). The speed of the block at

x=7\,\text{m}

is (a)

6.3\,\text{m\,s}^{-1}

(b)

4\,\text{m\,s}^{-1}

(c)

3.46\,\text{m\,s}^{-1}

(d)

5.3\,\text{m\,s}^{-1}