A wood block is placed on a rough surface. The surface starts horizontal, and one end is then raised so that the angle the surface makes with the horizontal gradually increases until, at an angle θ , the block begins to move down the surface, as shown in the figure. From this observation, which of the following can be concluded for angles greater than θ ? A) there is no frictional force on the block.

B) The gravitational force is equal to the frictional force.

C)The component of the gravitational force along the surface is greater than the frictional force.

D)The normal force is equal to the gravitational force.

E )The component of the normal force along the surface is greater than the gravitational force.

Which of the following elements is in the same period as phosphorus? a. carbon c. nitrogen b. magnesium d. oxygen select the best answer from the choices provided a b c d

Explain why electric current cannot exist if a current doesn't have a voltage source.

Astudent throws a water balloon with speed v0 from a height h = 1.76 m at an angle θ = 21° above the horizontal toward a target on the ground. the target is located a horizontal distance d = 9.5 m from the student’s feet. assume that the balloon moves without air resistance. use a cartesian coordinate system with the origin at the balloon's initial position. (a) what is the position vector, rtarge t, that originates from the balloon's original position and terminates at the target? put this in terms of h and d, and represent it as a vector using i and j. (b) in terms of the variables in the problem, determine the time, t, after the launch it takes the balloon to reach the target. your answer should not include h. (c) create an expression for the balloon's vertical position as a function of time, y(t), in terms of t, vo, g, and θ. (d) determine the magnitude of the balloon's initial velocity, v0, in meters per second, by eliminating t from the previous two expressions.