Physics Exam #2

Which of the following is NOT a vector? A)displacement B) speed C) velocity D) acceleration

speed

The magnitde of -->A is 5.5. Vector A lies in the second quadrant and forms an angle of 34 degrees with the y-axis. The components Ax and Ay are closest to: A) Ax= -4.6, Ay= +3.1 B) Ax= -3.1, Ay= +4.6 C) Ax= +3.1, Ay= -4.6 D) Ax= +4.6, Ay= -3.1 E) Ax= -4.6 Ay= -3.1

B) Ax= -3.1, Ay= +4.6

Vector A has length 2 units and directed to the north. Vector B has a length of 6 units and is directed to the south. Calculate the magnitude and direction of A-B.

B)8 units north

For general projectile motion, when the projectile is at the highest point of its trajectory A) the horizontal component of its velocity is zero B) the horizontal and vertical components of its velocity are zero C) its velocity and acceleration are both zero D)its velocity is perpendicular to the acceleration E) its acceleration is zero

D) the velocity is perpendicular to the acceleration

Two bullets are fired simultaneously parallel to a horizontal plane. The bullets have different masses and different initial velocities. Which one will strike the plane first? A) the fastest one B) the slowest one C) the heaviest one D) the lightest one E) They strike the plane at the same time.

E) They strike the plane at the same time

A car is being towed at constant velocity on a horizontal road using a horizontal chain. The tension in the chain must be equal to the weight of the car in order to maintain constant velocity. True or False

False

A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point down the ramp. True or False

False

You can launch a projectile with a fixed initial speed but at any angle above the horizontal, and it feels no air resistance. The time for it to return to the ground does not depend on the angle at which you launch it. True or False

False

The magnitude of a vector cannot be smaller than the magnitude of any of its components True or False

True

Two identical projectiles are launches with equal speeds from the top of a building and feel no air resistance. Projectile A is launched above the horizontal while projectile B is launched below the horizontal. Both projectiles have exactly the same acceleration while they are in the air. True or False

True

suppose you are playing hockey on a new-age ice surface for which there is no friction between the ice and the hockey puck. You wind up and hit the puck as hard as you can. After the puck loses contact with your stick, the puck will A) speed up a little, and then move at a constant speed B) speed up a little, and then slow down C) start to slow down D) not slow down or speed up

not slow down or speed up

An object is moving forward with a constant velocity. Which statement about this object MUST be true? A) the net force on the object is in the forward direction B) the acceleration of the object is in the forward direction C) No forces are acting on the object D) the net force on the object is zero

the net force on the object is zero

A ball is tossed vertically upward. When it reaches its highest point (before falling back downward)

the velocity is zero, the acceleration is pointed downward, and the force of gravity acting on the ball is directed downward

You throw a 5.0 kg stone from the top of a cliff with an initial vertical velocity of 8.0 m/s downward and an initial horizontal velocity of 7.0 m/s away from the cliff, and it feels no air resistance. After the stone is in the air but free of your hand, its acceleration remains constant at 9.8 m/s2 downward but its speed changes. True or False

true