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2 years ago

A brick is resting on a rough incline as shown in the figure. The friction force acting on the brick, along the incline, is

Physics

2 answers:

Tasya [4]2 years ago

6 0

B) equal to the gravitational force of the brick

lakkis [162]2 years ago

4 0

Answer:

D) less than the gravitational force of the brick.

Explanation:

When a brick is at rest on the inclined plane

then we will have all forces balanced on the brick

so we will have force balance along the inclined plane given as

$F_g sin\theta = F_f$

$mg sin\theta = F_f$

on the other side we can find force balance perpendicular to the inclined plane

$mg cos\theta = F_n$

so from above equation we can say that friction force is the component of the weight of the object along the inclined plane

so correct answer is

D) less than the gravitational force of the brick.

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A gas is compressed from 600 cm3 to 200cm3 at a constant pressure of 400 kpa. at the same time, 100 j of heat energy is transfer

Mekhanik [1.2K]

The initial volume of the gas is
$V_i = 600 cm^3$
while its final volume is
$V_f = 200 cm^3$
so its variation of volume is
$\Delta V = V_f - V-i = 200 cm^3 - 600 cm^3 = -400 cm^3 = -400 \cdot 10^{-6} m^3$

The pressure is constant, and it is
$p=400 kPa = 400 \cdot 10^3 Pa$

Therefore the work done by the gas is
$W=p\Delta V = (400 \cdot 10^3 Pa)(-400 \cdot 10^{-6} m^3)=-160 J$
where the negative sign means the work is done by the surrounding on the gas.

The heat energy given to the gas is
$Q=+100 J$

And the change in internal energy of the gas can be found by using the first law of thermodynamics:
$\Delta U = Q-W = 100 J - (-160 J)=+260 J$
where the positive sign means the internal energy of the gas has increased.

7 0

2 years ago

A sports car accelerates from 0 to 30 mph in 1.5 s. How long would it take to accelerate from 0 to 60 mph, assuming the power of

Crank

Answer:

6 s

Explanation:

given,

Sports car accelerate from 0 to 30 mph in 1.5 s

time taken to accelerate 0 to 60 mph = ?

The power of the engine is independent of velocity and neglecting friction

power =

P = constant

the kinetic energy for 60 mph larger than this of 30 mph

= $\dfrac{\dfrac{1}{2}mv_1^2}{\dfrac{1}{2}mv_2^2}$

= $\dfrac{v_1^2}{v_2^2}$

= $\dfrac{60^2}{30^2}$

= 4

gain in kinetic energy = P x t

time = 4 x 1.5

= 6 s

8 0

2 years ago

You decide to work at a heart rate of 150 instead of 120. What area of F.I.T.T. did you change?

Rina8888 [55]

Key concepts

Heart rate

Exercising

The heart

Cardiovascular system

Health

Introduction

As Valentine's Day approaches, we're increasingly confronted with "artistic" images of the heart. Real hearts hardly resemble to two-lobed shapes adorning cards and candy boxes this time of year. And the actual shape of the human heart is important for its function of supplying blood to the entire body. You have likely noticed that your heart beats more quickly when you exercise. But have you ever taken the time to observe how long it takes to return to its normal rate after you're done exercising? In this science activity you'll get to do some exercises to explore your own heart-rate recovery time.

Background

Your heart is continuously beating to keep blood circulating throughout your body. Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise—to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level. Because your heart is also a muscle, exercise, in turn, helps keep it healthy. The American Heart Association recommends that a person does exercise that is vigorous enough to raise their heart rate to their target heart-rate zone—50 percent to 85 percent of their maximum heart rate, which is 220 beats per minute (bpm) minus their age for adults—for at least 30 minutes on most days, or about 150 minutes a week in total. So for a 20-year-old, the maximum heart rate would be 200 bpm, with a target heart-rate zone of 100 to 170 bpm. (For those 19 or younger, target zones can vary more than they do for adults.)

i think it will help you...if it help you ...please mark brainless

8 0

2 years ago

Fig. 19-4 shows two wires, in cross section, carrying 7.0 Amperes out of the page. Determine the total magnetic field, due to bo

mel-nik [20]

I habe no idea i just need points sorry

6 0

2 years ago

A skydiver is using wind to land on a target that is 50 m away horizontally. The skydiver starts from a height of 70 m and is fa

elena55 [62]

Answer:

Answer:

15.67 seconds

Explanation:

Using first equation of Motion

Final Velocity= Initial Velocity + (Acceleration * Time)

v= u + at

v=3

u=50

a= - 4 (negative acceleration or deceleration)

3= 50 +( -4 * t)

-47/-4 = t

Time = 15.67 seconds

6 0

2 years ago