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.

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

What effects result when there is an impact between earth and an asteroid? check all that apply. a.massive flooding. b.extinction of many life forms.c.major earthquakes change in average global temperature.d. giant dust cloud

How much energy is supplied to each coulomb of charge that flows through a 12-v battery?