PHYSICAL SCIENCE

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m Is. The girl's speed is a. 0.45 m/s. b. 0.55m/s. c. 0.83 m/s. d. 1.2 m/s.

0.83 m/s

A commercial jet has a mass of 5,000 kg and the thrust of its engine is 10,000 N. The acceleration of the jet when taking off is ?

2 m/s2

Exert 100 J in 50 s and your power output is a. 1/4 W. b. 1/2 W. c. 2W. d. 4W. e. more than 4 W.

2w

A girl pulls a 10 kg wagon with a constant force of 30 N. What is the wagon's acceleration?

3.0 m/s2

If a ball rolls down an inclined plane and picks up 4 m/s each second it rolls, its acceleration is?

4 m/s squared

A man weighing 800 N stands at rest on two bathroom scales so that one scale shows a reading of 500 N. The reading on the other scale is? A.) 800 N. B.) 400 N. C.) 200 N. D.) 300 N. E.) none of the above

400 N

Burl and Paul have a total weight of 1300 N. The tensions in the ropes that support the scaffold they stand on add to 1700 N. The weight of the scaffold itself must be ?

400 N

An object falls with constant acceleration, the velocity of the object must A) be constant also. B) continuously change by the same amount each second. C) continuously change by varying amounts depending on its speed. D) continuously decrease. E) none of these.

Continuously change by the same amount each second

An object is pulled with two forces, 10 N northward and 15 N southward. The direction of the net force is to the?

South

A sheet of paper can be pulled from beneath a box of cereal without toppling it if the paper is jerked quickly. This best demonstrates that A) the box has no acceleration. B) there is an action-reaction pair of forces. C) gravity tends to hold the box secure. D) the box has inertia.

The box has inertia

When you push a crate across a level floor at constant speed, friction between the crate and the floor is?

The same amount as your pushing force

In order to catch a fast moving softball with you bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the...

Time of catch is increased

If the mass of an object does not change, a constant net force on the object produces constant A) velocity. B) acceleration. C) both of these D) none of these.

acceleration

The force of an apple hitting the ground depends on a. the speed of the apple just before it hits. b. the time of impact with the ground. c. whether or not the apple bounces. d. all of these

d. all of these (speed just before it hits, time of impact, whether or not the apple bounces)

The two measurements necessary for calculating average speed?

distance and time

If a charging rhino has momentum, it must also have?

kinetic energy

Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has the same? A. volume. B. weight. C. mass. D. all of the above E. none of the above

none of the above

The equilibrium rule, ∑F=0, applies to?

objects or systems at rest OR objects or systems in uniform motion in a straight line

When a rock thrown straight upwards gets to the exact top of its path, its

velocity is zero and its acceleration is about 10 m/s2 second per second

A ball is thrown upward and caught when it comes back down. When air resistance affects the ball, compared with the initial upward speed, the speed when caught is

More

An object that has kinetic energy must be?

Moving

Two identical arrows, one with twice the kinetic energy of the other, are fired into a hay bale. The faster arrow will penetrate a. the same distance as the slower arrow. b. twice as far as the slower arrow. c. four times as far as the slower arrow. d. more than four times as far as the slower arrow. e. none of these

Four times as far as the slower arrow.

Your weight is your what?

Gravitational attraction between you and earth

A kilogram is a measure of an object's?

Gravity

If you are carrying a heavy bag of groceries and bang your hand against the wall, the concept that best explains why you are hurt is?

Inertia

A falling object that has reached its terminal speed continues to gain

Neither(Speed or acceleration)

The conservation of momentum is closely related to?

Newton's third law

If you push for an hour against a stationary wall, you do no work A) on the wall. B) at all. C) both of these D) none of these

On the wall

Compared with falling on a wooden floor, a wine glass may not break when it falls to a carpeted floor because of the?

Longer time to stop

In contrast to Aristotle's way of explaining nature, Galileo relied on?

Experiment