Question

Calculate the amount of work done if you use a 100N force to push a 50kg box 5m across the kitchen floor.

A)
250 J


B)
500 J


C)
5000 J


D)
50,000 J


2)
Tommy was walking at a rate of 4
miles
hour
at noon and at 12:30 pm he was walking at a brisk rate of 6
miles
hour
. Two hours later Tommy was walking at a leisurely rate of 2
miles
hour
. Which statement about Tommy's accleration is true?

A)
Tommy had an accleration of zero the entire time.


B)
Tommy had a positive acceleration between noon and 12:30 pm.


C)
Tommy had a positive acceleration between 12:30 and 2:30 pm.


D)
Tommy had a negative acceleration between noon and 12:30 pm.


3)
Gravity is a force between any two objects with mass. Why doesn't a person feel a gravitational force between him/herself and another person?

A)
A person doesn't exert a gravitational force.


B)
The two gravitational forces cancel each other out.


C)
The gravitational forces of people is so small it is overshadowed by that of Earth.


D)
There are so many people we are actually balanced by all the different gravitational forces.


4)
Four wrestlers step on a scale for a tournament. Wrestler A weighs in at 170 pounds; wrestler B weighs in at 168 pounds; wrestler C weighs in at 171 pounds; and wrestler D weighs in at 169 pounds. Which of these wrestlers experiences the greatest force due to gravity?

A)
Wrestler A


B)
Wrestler B


C)
Wrestler C


D)
Wrestler D


5)



Consider the substance represented by the heating curve. What is the MOST accurate conclusion can you draw about the vaporization of the substance?

A)
Heat of fusion equals heat of vaporization.


B)
The melting point is half the boiling point.


C)
It takes the substance longer to vaporize than it does to condense.


D)
It requires much more energy to vaporize the substance than to melt it.


6)



Which BEST describes the speed and velocity of the graph?

A)
Both speed and velocity are changing.


B)
The speed and velocity remain constant.


C)
The speed is constant and velocity is changing.


D)
The velocity cannot be determined from the graph.


7)



At the county fair, Carrie and Sam climbed up on the carousel horses. Around and around they went; the horses also bobbed up and down. When they got off of the carousel, Carrie told Sam they had been accelerating during their ride. Sam disagreed; they had been moving at a constant speed. Whose response is fully correct, and why?

A)
Carrie is, because the carousel changed speed when it started and stopped.


B)
Sam is, because the horses never moved from their position on the carousel.


C)
Carrie is, because velocity includes speed plus direction, and both changed.


D)
Sam is, they did not accelerate since their speed remained constant for the ride.


8)
A fan is connected to a battery in a series circuit. What kind of energy transfer occurs if the circuit is closed?

A)
Light energy changes to chemical energy.


B)
Thermal energy changes to mechanical energy.


C)
Chemical energy changes to mechanical energy.


D)
Mechanical energy changes to chemical energy.


9)




Sam and Sally are both running the mile at the region track meet. One mile equals four laps around the oval track. They are neck and neck during most of the race, but at the half-mile mark Sam starts to pull ahead. He wins the race with a time of 5 minutes 25 seconds. Sally stops at .9 miles to have a drink of water and then continues to the finish line.

How does Sam and Sally's displacement compare for the race?

A)
Their displacement is the same, zero miles.


B)
Sam's displacement is greater than Sally's.


C)
Sally's displacement is greater than Sam's.


D)
Both Sam and Sally's displacement is 1 mile.


10)
To lift a load of 100 kg a distance of 1 m an effort of 25 kg must be applied over an inclined plane of length 4 m. What must be done to lift the load 2 m, using the same effort?

A)
Use an inclined plane of length 8 m.


B)
Use an inclined plane of length 2 m.


C)
Use an inclined plane of length 10 m.


D)
Use an inclined plane of length 16 m.

Answer 1

The answer is B Because i took the test and what you look up you is not all of this. (hope this helps)

Answer 2

1) B) 500 J

The amount of work done is equal to the product between the force applied (F=100 N) and the distance covered by the box (d=5 m):

`W=Fd=(100 N)(5 m)=500 J`

2) B) Tommy had a positive acceleration between noon and 12:30 pm.

In fact, Tommy's velocity increases between noon and 12.30 pm (at noon, he travels at 4 mph, while at 12.30 pm he travels at 6 pm). Since acceleration is equal to the rate of chang in velocity, an increase in velocity means a positive acceleration.

3) C) The gravitational forces of people is so small it is overshadowed by that of Earth

The magnitude of the gravitational force is given by:

`F=G(m_1 m_2)/(r^2)`

where G is the gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between the two objects. From this formula we can understand that the gravitational force exerted by a man on another man is negligible compared to the gravitational force exerted by the Earth on a man, since the Earth's mass is much greater than the mass of a man.

4) C) Wrestler C

The force due to gravity is equal to the weight of the wrestler:
`W=mg`, where m is the mass of the wrestler and g is the acceleration due to gravity. Since wrestler C has the greatest mass (171 pounds), it has the largest weight, so it experiences the largest force due to gravity.

5) the graph here is missing.

6) the graph here is missing.

7) C) Carrie is, because velocity includes speed plus direction, and both changed.

An object is accelerating when its velocity changes. But velocity includes both speed and direction: therefore, an object is accelerating when either its speed or its direction is changing. In this example, we are told that Carrie and Sam go up and down in the carousel, therefore their velocity is changing direction, so they are accelerating for sure.

8) C) Chemical energy changes to mechanical energy.

The energy of the battery is chemical energy, and this is converted into kinetic energy (due to the motion of the fan), which is mechanical energy.

9) A) Their displacement is the same, zero miles

Displacement is equal to the difference between the final position and the initial position. Since the mile consists of 4 entire laps, it means that the two guys will return at their starting point at the end of the mile: therefore, their displacement is zero.

10) A) Use an inclined plane of length 8 m.

If we want to use the same effort, we must keep the proportions of the inclined plane the same as in the first example. In the first example, the ratio between the length of the incline and its height is 4:1, and since in the second example the height is increased to 2 m, to keep the same proportions the new ratio should be 8:2, so the length of the inclined plane must be 2 m.