Physical Science I Midterm

A car is moving down a freeway in a straight line at a constant rate of 24.0 m/s for 4.0 s. Its acceleration is

0

An automobile traveling on a straight, level road at 15 km/h speeds up to 90 km/h in 30 s. Expressed in units of meters per second squared and rounded to two decimal places, the magnitude of the automobile's acceleration is _____ meters per second squared. (Useful information: 1 m/s = 3.60 km/h)

0.69

If an unbalanced force of 6 N force acts on a 7-kg object, what is its acceleration?

0.86 m/s2

A force of 7.2 N acting on a 1.0-kg object initially at rest moves it through a parallel distance of 2.5 m. This means that _________ J of work is done on the object. Type your answer in numerical form.

18

A student weighing 200 N climbed a flight of stairs 9.0 m high in 4 s. How much work was done by the student?

1800 joules

A 50 kg boy on skates pushes against a wall with a force of 25 N. How hard does the wall push against him, and what magnitude of acceleration does he experience?

25N and an acceleration of 0.5m/s2

A stone is dropped from the top of a well that has water in it at a depth of 65.0 m. It would take the stone ____ s to reach the water. Express your answer rounded to two decimal places.

3.64

A 50 kg child is riding on a merry-go-round at 3 m/s. How much angular momentum does the child have if seated 2.0 m from the center of the merry-go-round?

300kg-m/s2

A golfer hits a ball on a level fairway at an angle of 55 degrees relative to the horizontal, and it lands on the green. Another golfer hits a ball with the same speed but at another angle, and it lands on the green by the other ball. What was the launch angle for the second golfer?

35 degrees

If an object of mass 7 kg has a velocity of 5 m/s, what is its linear momentum?

35kg-m/s

A student weighing 300 N climbs a flight of stairs 7.0 m high in 8 s. What power is required to perform this task?

38 W

An object of mass 6 kg has a speed of 4 m/s and moves a distance of 2 m. What is its kinetic energy in joules?

48

If an object of mass 9 kg has an acceleration of 6 m/s2, what is the unbalanced force acting on it?

54N

An object is pulled northward with a force of 10 N and southward with a force of 15 N. The magnitude of the net force on the object is

5N

An object with a mass of 8 kg is dropped and takes 5 s to hit the ground. Then another object with a mass of 16 kg is dropped from the same point. How long does it take to hit the ground?

5s

The weight of 0.6 kg of salami on Earth is approximately

6N

If the lever arm of an 8 N force is 9 m, what is the torque acting on the object due to this force?

72 N-m

On a trip, a family travels 200 km in 2.5 h on the first day, 300 km in 4.0 h on the second day, and 250 km in 3.5 h on the third day. The average speed for the total trip is _____ km/h. Express your answer as a number.

75

An object has kinetic energy of 324 J. If its speed is 9 m/s, what is its mass in kilograms?

8

The magnitudes of two horizontal displacements are 6 m and 3 m, respectively. Given that the vectors may be in either the plus or minus direction, they cannot be added together to give a total displacement of

A. 2m b. -3 c. 9 d. 3

The acceleration produced by an unbalanced force acting on an object is

ALL OF THESE in the direction of force directly proportional to the magnitude of the force inversely proportional to the mass of the object.

If an object moves with constant velocity,

ALL OF THESE its speed, direction and average speed are constant

Which of the following is not a unit of power?

N *m

Which of the following is a vector quantity?

NONE OF THESE energy, power, work

Motion necessarily involves

a change in position

An object in free fall has

a velocity that changes 9.8 m/s each second.

The rate at which an object's velocity changes with time is called its

acceleration

Which of the following four objects has the greatest kinetic energy?

an object of mass 2m moving with speed 3v

A mass is accelerated when ______________ acts upon the mass.

an unbalanced force

Displacement divided by time gives

average velocity

A 10 kg rock and a 1 kg rock are dropped simultaneously from the same height. If air resistance is neglected,

both rocks hit the ground at the same time, but the 10 kg rock has a greater momentum.

To cause an object to move in a circle, a(n) ______________ force is necessary.

centripetal

An object in uniform circular motion has

constant speed

An object that is moving in a linear path with an acceleration in the direction opposite to the motion has a(n) ______________ velocity.

decreasing

Velocity is similar to speed, but a ________ is also involved in velocity.

direction

Average speed multiplied by time gives

distance

If you lift a 10-N weight vertically 10 m above the ground, you are

doing work against gravity

What is bought from an electric company?

electrical energy

Physics deals with matter, motion, force, and ________________.

energy

An object is dropped from a vertical distance of 31.7 m above the ground, and it takes 2.54 s to fall that distance. A second identical object is launched from the same height, with a horizontal velocity of 64.0 m/s. Neglecting air resistance, how long does the second object take to fall the 31.7 m?

exactly 2.54s

A spacecraft in space keeps going at the same velocity, even without firing its rockets, in accordance with the _______________ law of motion.

first

An object will ______________ in a fluid if its average density is ______________ the density of the fluid.

float; less than

Mass is a measure of

grams

A sheet of paper can be withdrawn from under a milk carton without toppling it if the paper is jerked quickly. This best demonstrates that:

gravity tends to hold the milk carton more secure

An object that is moving in a linear path with an acceleration in the direction of motion has a(n) ______________ velocity.

increasing

A speedometer indicates ______________ if the automobile is traveling forward.

instantaneous speed

In the equation A = B/C, the A and C are _______________ proportional.

inversely

The SI base units making up the newton are

kg-m/s2

The energy of motion is called

kinetic energy

The speed of a comet in its orbit around the Sun is ______________ when its distance from the Sun is greatest.

least

One watt is equal to ______________ per second.

one joule

Work is defined as force times

parallel distance

The energy of position is called

potential energy

We define the total mechanical energy of an object as

potential plus kinetic energy

All the following may be represented by vectors except

speed

Distance covered per unit of time is called

speed

An automobile's acceleration may be changed by using the

steering wheel

The distance traveled by a dropped object in free fall is directly proportional to

the time squared

"For every action there is an equal and opposite reaction" is a statement of Newton's

third law

Newton's law of universal gravitation is believed to be applicable

throughout the universe

Power is

time of rate of doing work

An object travels in a circle of radius 3.0 m with a constant speed of 4.0 m/s. What is the direction of its acceleration?

toward the center of the circle

In projectile motion, which of the following is not constant?

verticle velocity

Which of the following is not a unit of work?

watt

Two equal and opposite forces of 5.0 N act on an object. The unbalanced force on the object is

zero N