Halving the kelvin temperature of a gas in a rigid container decreases the gas pressure by one half.

Does an athlete do work on a trophy as she lifts it overhead

bogdanovich [222]

No she/he is doing work for her muscles

3 0

3 years ago

A man is flying in a hot-air balloon in a straight line at a constant rate of 5 feet per second, while keeping it at a constant

icang [17]

Answer:

$x = 220.85 ft$

Explanation:

Let at any moment of time the friend's car is at some horizontal distance "x" from the position of balloon.

Now if the altitude of the balloon is fixed and it is at height "h"

so here we will have

$tan \theta = \frac{h}{x}$

now we know that

initially the angle of the friend's car is 35 degree

so the horizontal distance will be

$x_1 = h cot35$

similarly if the angle after passing the car position is 36 degree

then we have

$x_2 = h cot36$

now the speed of the balloon is constant

so we have

$v = \frac{x_1 + x_2}{\Delta t}$

$5 ft/s = \frac{h cot35 + h cot36}{90 s}$

$5 ft/s = \frac{2.8h}{90}$

$h = 160.45 ft$

so the final position of friend when the angle is 36 degree

$x = \frac{h}{tan36}$

$x = \frac{160.45}{tan36}$

$x = 220.85 ft$

4 0

3 years ago

A man pushes a shopping cart at a constant speed. What happens if the man increases the force on the cart?

Bezzdna [24]

Answer:

The cart would speed up.

Explanation:

According to Newton's 1st law, object subjected to no force, or net force 0, would have a constant speed. In our case the cart is initially at constant speed, meaning the man exerts a force that is equal to friction force. If he increases the force on the cart, the net force would no longer be 0. The cart would gain an acceleration and increases its speed.

4 0

3 years ago

The filament in a light bulb uses 2.55 amps when the voltage is 175 volts. What is the resistance?

Naddika [18.5K]

Resistance = (voltage) / (current)

= (175 v) / (2.55 Amperes)

= 68.6 ohms .

3 0

3 years ago

A brick 25cm long ,9cm wide 5cm thick has a mass of 1000g determine the greatest pressure that can be exerted by the brick on a

lana66690 [7]

Answer:

<em>The greatest pressure is 2178 Pa</em>

Explanation:

<u>Pressure</u>

It's the force applied perpendicular to the surface of an object per unit area over which the force is distributed.

If F is the force applied and A is the surface area, the pressure is calculated as:

$\displaystyle P=\frac{F}{A}$

The brick has dimensions of 25 cm by 9 cm by 5 cm. There are three possible areas of contact:

$A_1=25*9 = 225 cm^2=0.0225\ m^2$

$A_2=25*5= 125 cm^2=0.0125\ m^2$

$A_3=9*5= 45 cm^2=0.0045\ m^2$

The brick has a mass of m=1000 g = 1 Kg and exerts a force equal to its weight when placed on a flat surface, thus:

F = m.g = 1 * 9.8 = 9.8 N

The greatest possible pressure will occur when the area is the least possible $(0.0045\ m^2)$ , since the pressure and the area are inversely proportional, thus:

$\displaystyle P_{max}=\frac{9.8}{0.0045}$

$\displaystyle P_{max}=2178 \ Pa$

The greatest pressure is 2178 Pa

8 0

3 years ago