Quiz #3

A stone is being accelerated vertically upward by a string attached to it. Now suppose the string breaks and the stone slows in its upward motion. What is the acceleration of the stone at the top of its path?

10.0 m/s2

Forces of 2.6 N and 5.0 N act at right angles on a block of mass 2.5 kg . Find the acceleration of the block.

a = 2.3 m/s2

A piece of rope is pulled by two people in a tug-of-war. Each exerts a 400-N force. What is the tension in the rope? a) 400 N b) 800 N c) 600 N d) zero e) none of the above

a) 400 N

As a ball falls, the action force is the Earth's pull on the ball. The reaction force is the a) ball's pull on Earth. b) acceleration of the ball. c) air resistance acting against the ball. d) none of the above

a) ball's pull on Earth.

When a boxer hits a punching bag, the strength of his punch depends on how much force the bag can a) exert on the boxer's fist. b) soften. c) endure.

a) exert on the boxer's fist.

The attraction between Earth and Sydney is equal to her weight. The reaction to Earth's pull on Sydney is a) Sydney pushing against Earth's surface. b) Sydney's pull on Earth. c) the support of Earth's surface on Sydney. d) none of the above

b) Sydney's pull on Earth.

An archer shoots an arrow. Consider the action force to be the bowstring against the arrow. The reaction to this force is the a) combined weight of the arrow and bowstring. b) arrow's push against the bowstring. c) air resistance against the bow. d) grip of the archer's hand on the bow. e) friction of the ground against the archer's feet.

b) arrow's push against the bowstring.

When a rocket forces exhaust gases downward, the exhaust gases a) play no further role in the motion of the rocket. b) exert an upward force on the rocket. c) as the name implies, soon exhaust their influence.

b) exert an upward force on the rocket.

To produce an acceleration to a system there a) must be acceleration outside the system also. b) must be a net force on the system. c) may or may not be a net force on the system.

b) must be a net force on the system.

When you walk, you push on the floor to the left and the floor a) both of these simultaneously. b) pushes you to the right. c) can only wish it could push on you. d) also pushes on you to the left. e) none of the above

b) pushes you to the right.

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is a) greater on the bug. b) greater on the car. c) the same for both.

c) the same for both.

Two equal-size vectors at right angles to each other have a resultant that is a) twice the length of either vector. b) equal to that of either vector. c) √2 the length of either vector.

c) √2 the length of either vector.

When Nellie hangs suspended from a pair of ropes that are not vertical, the tension in each rope is a) half her weight. b) less than half her weight. c) her weight. d) more than half her weight.

d) more than half her weight.

Three kids pull on a toy. Kim pulls with a force of 30 N north, Jim pulls with a force of 30 N south, and Tim pulls with a force of 15 N east. The acceleration of the toy is a) 15 m/s2. b) 10 m/s2. c) 33 m/s2 d) need more information

d) need more information

Neglecting air resistance, once a tossed ball leaves your hand a) inertia becomes the force acting on it. b) your tossing force remains while the ball goes upward. c) no further forces act on it. d) only the force due to gravity acts on it. e) your tossing force remains until it comes to a stop.

d) only the force due to gravity acts on it.