All categories

2 years ago

What is the efficiency of a car's engine when heat input is 400,000 joules and

Physics

2 answers:

Aleksandr-060686 [28]2 years ago

5 0

Either 25% or 75%. does it to how much is wasted or the difference in the input and waste?

otez555 [7]2 years ago

3 0

Answer: A. 25%

Explanation: Ap3x

You might be interested in

How does an atom change if all of its electrons are removed?

Alex

<span>The atom becomes positively charged.

When you add electrons to a neutral atom, it is no longer a neutral atom, it has a negative change and is an anion. When you take away electrons from a neutral atom, it is no longer a neutral atom- it becomes a positive atom, and is a cation.</span>

6 0

2 years ago

A car is traveling at 50 mi/h when the brakes are fully applied, producing a constant deceleration of 38 ft/s2. what is the dist

e-lub [12.9K]

Convert 38 ft/s^2 to mi/h^2. Then we se the conversion factor > 1 mile = 5280 feet and 1 hour = 3600 seconds.

So now we show it > $38 \frac{ft}{s^2} x \frac{1mi}{5280ft} x \frac{(3600s)^2}{(1h)^2} = 93272.27 \frac{mi}{h^2}$

Then we have to use the formula of constant acceleration to determine the distance traveled by the car before it ended up stopping.

Which the formula for constant acceleration would be > $v_2^2=v_1^2 + 2as$

The initial velocity is 50mi/h $(v_1=50)$

When it stops the final velocity is $(v_2=0)$

Since the given is deceleration it means the number we had gotten earlier would be a negative so a = -93272.27

Then we substitute the values in....

$0^2 = 50^2 + 2(-93272.27)s

0 = 2500 - 186544.54s

Isolate S next.

185644.54s= 2500

s = 2500/(185644.54)

s=0.0134
$

So we can say the car stopped at 0.0134 miles before it came to a stop but to express the distance traveled in feet we need to use the conversion factor of 1 mile = 5280 feet in otherwards > $0.0134 mi * \frac{5280ft}{1mi} = 70.8 ft$
So this means that the car traveled in feet 70.8 ft before it came to a stop.

4 0

2 years ago

Period T= time of one revolution measured in seconds

ser-zykov [4K]

60 RPM equals one hertz (i.e., one revolution per second, or a period of one second). The SI unit for period is the second.

3 0

2 years ago

A solid circular disk has a mass of 1.2 kg and a radius of 0.16m. Each of three identical thin rods has a mass of 0.16kg. The ro

Juli2301 [7.4K]

Answer:

0.027648 kgm²

Explanation:

M = Mass of disc = 1.2 kg

r = Radius of disc = 0.16 m

m = Mass of rod = 0.16 kg

R = Rod distance = 0.16 m

Moment of inertia of disk is given by

$I_1=\dfrac{1}{2}Mr^2\\\Rightarrow I_1=\dfrac{1}{2}1.2\times 0.16^2\\\Rightarrow I_1=0.01536\ kgm^2$

Moment of inertia of the three rods

$I_2=3mr^2\\\Rightarrow I_2=3\times 0.16\times 0.16^2\\\Rightarrow I_2=0.012288\ kgm^2$

The total moment of inertia is given by

$I=I_1+I_2=0.01536+0.012288\\\Rightarrow I=0.027648\ kgm^2$

The moment of inertia of the stool with respect to an axis that is perpendicular to the plane of the disk at its center is 0.027648 kgm²

8 0

3 years ago

A wheel of mass 4kg is pulled up a plane inclined at 30° to the horizontal by a force of 45N applied to the axle and parallel to

Len [333]

Answer:

v = 10 m/s

Explanation:

Let's assume the wheel does not slip as it accelerates.

Energy theory is more straightforward than kinematics in my opinion.

Work done on the wheel

W = Fd = 45(12) = 540 J

Some is converted to potential energy

PE = mgh = 4(9.8)12sin30 = 235.2 J

As there is no friction mentioned, the remainder is kinetic energy

KE = 540 - 235.2 = 304.8 J

KE = ½mv² + ½Iω²

ω = v/R

KE = ½mv² + ½I(v/R)² = ½(m + I/R²)v²

v = √(2KE / (m + I/R²))

v = √(2(304.8) / (4 + 0.5/0.5²)) = √101.6

v = 10.07968...

5 0

2 years ago