To practice tactics box 9.1 calculating the work done by a constant force. recall that the work w done by a constant force f⃗ at an angle θ to the displacement δr⃗ is w=f⃗ ⋅ δr⃗ =fδrcosθ. the vector magnitudes f and δr are always positive, so the sign of w is determined entirely by the angle θ between the force and the displacement.

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is

World class speed skaters can skate a 3,000-m course in about 4 minutes.what is their average speed for this course? a. 12.5 m/sb. 1.33 m/sc. 1.25 m/sd. 13.3 m/s

Abaseball is thrown from the outfield toward the catcher. when the ball reaches its highest point, which statement is true? (a)its velocity is not zero, but its acceleration is zero. (b) its velocity and its acceleration are both zero. (c) its velocity is perpendicular to its acceleration. (d) its acceleration depends on the angle at which the ball was thrown. (e) none of the above statements are true.