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butalik [34]
3 years ago
6

Driving on asphalt roads entails very little rolling resistance, so most of the energy of the engine goes to overcoming air resi

stance. But driving slowly in dry sand is another story. If a 1200 kg car is driven in sand at 5.2 m/s, the coefficient of rolling friction is 0.06. In this case, nearly all of the energy that the car uses to move goes to overcoming rolling friction, so you can ignore air drag in this problem.
a. What propulsion force is needed to keep the car moving forward at a constant speed?

b. What power is required for propulsion at 5.2 m/s?
If the car gets 15 mpg when driving on sand, what is the car's efficiency? Assume the density of gasoline is 719.7 kg/m^3.
Help please!
Physics
1 answer:
Bad White [126]3 years ago
8 0
A) Agreed. 
<span>b) Value agreed but units should be W (watts). </span>

<span>c) Here's one method... </span>

<span>15 miles = 24140 m </span>

<span>1 gallon of gasoline contains 1.4×10⁸ J. </span>

<span>So moving a distance of 24140m requires gasoline containing 1.4×10⁸ J </span>

<span>Therefore moving a distance of 1m requires gasoline containing 1.4×10⁸/24140 = 5800 J </span>

<span>Overcoming rolling resitance for 1m requires (useful) work = force x distance = 1000x1 = 1000J </span>

<span>So 5800J (in the gasoline) provides 1000J (overcoming rolling resistance) of useful work for each metre moved. </span>

<span>Efficiency = useful work/total energy supplied </span>
<span>= 1000/5800 </span>
<span>= 0.17 (=17%) </span>
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LVULAN
3241004551 [841]

For this case we have that by definition, the kinetic energy is given by the following formula:

k= \frac {1} {2} * m * v ^ 2

Where:

m: It is the mass

v: It is the velocity

According to the data we have to:

m = 100 \ kg\\v = 9 \frac {m} {s}

Substituting the values we have:

k = \frac {1} {2} * (100) * (9) ^ 2\\k = \frac {1} {2} * (100) * 81\\k = 50 * 81\\k = 4050

finally, the kinetic energy is 4050 \ J

Answer:

Option A

7 0
3 years ago
Which change in an object would increase the force needed to move the object​
creativ13 [48]

Answer:

force is the answer because force is pushing the item

6 0
3 years ago
The work done on a box is 532 joules. The force applied to the box was 48 N. What was the displacement of the box? *
Semenov [28]

Explanation:

Work = force × displacement

532 J = 48 N × d

d ≈ 11 m

8 0
3 years ago
g Power is _________________the force required to push something the work done by a system the speed of an object the rate that
Levart [38]

Answer:

the rate that the energy of a system is transformed

Explanation:

We can define energy as the capacity or ability to do work. Power is defined as the rate of doing work or the rate at which energy is transformed. It can also be regarded as the time rate of energy transfer. In older physics literature, power is sometimes referred to as activity.

Power is given by energy/time. Its unit is watt which is defined as joule per second. Another popular unit of power is horsepower. 1 horsepower = 746 watts.

Very large magnitude of power is measured in killowats and megawatts.

4 0
3 years ago
A burglar attempts to drag a 108 kg metal safe across a polished wood floor Assume that the coefficient of static friction is 0.
V125BC [204]

Answer:

2.00 m/s²

Explanation:

Given

The Mass of the metal safe, M = 108kg

Pushing force applied by the burglar,  F = 534 N

Co-efficient of kinetic friction, \mu_k = 0.3

Now,

The force against the kinetic friction is given as:

f = \mu_k N = u_k Mg

Where,

N = Normal reaction

g= acceleration due to the gravity

Substituting the values in the above equation, we get

f = 0.3\times108\times9.8

or

f = 317.52N

Now, the net force on to the metal safe is

F_{Net}= F-f

Substituting the values in the equation we get

 F_{Net}= 534N-317.52N

or

F_{Net}= 216.48

also,

 

F_{Net}= M\timesacceleration of the safe

Therefore, the acceleration of the metal safe will be

acceleration of the safe=\frac{F_{Net}}{M}

or

 acceleration of the safe=\frac{216.48}{108}

or

 

acceleration of the safe=2.00 m/s^2

Hence, the acceleration of the metal safe will be  2.00 m/s²

3 0
3 years ago
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