Physics, 28.08.2020 14:01 borsha255

(a) Calculate the kinetic energy, in joules of a 1200 -kg automobile moving at 18 m/s . (b) Convert this energy to calories.
(c) When the automobile brakes to a stop is the "lost" kinetic energy converted mostly to heat or to some form of potential energy?

Answers: 2

Show answers

Answers

a) The kinetic energy of the 1200-kg automobile moving at 18 meters per second is 194400 joules, b) The kinetic energy of the 1200-kg automobile moving at 18 meters per second is 46440.516 calories, c) the kinetic energy is transformed into work due to friction, which is a non-conservative force. And such work is dissipated in the form of heat.

Explanation:

a) Let be the automobile considered as particle travelling on horizontal ground, so that motion is entirely translational and whose formula for kinetic energy, measured in joules, is:

$K = \frac{1}{2}\cdot m \cdot v^{2}$

Where:

- Mass, measured in kilograms.

- Speed of automobile, measured in meters per second.

If $m = 1200\,kg$ and $v = 18\,\frac{m}{s}$ , the kinetic energy of the automobile is:

$K = \frac{1}{2}\cdot (1200\,kg)\cdot \left(18\,\frac{m}{s} \right)^{2}$

$K = 194400\,J$

The kinetic energy of the 1200-kg automobile moving at 18 meters per second is 194400 joules.

b) A calory equals 4.186 joules. The kinetic energy in calories is:

$K = 194400\,J \times \left(\frac{1}{4.186}\,\frac{cal}{J} \right)$

$K = 46440.516\,cal$

The kinetic energy of the 1200-kg automobile moving at 18 meters per second is 46440.516 calories.

c) When the automobile brakes to a stop, the kinetic energy is transformed into work due to friction, which is a non-conservative force. And such work is dissipated in the form of heat. Hence, such energy cannot be recovered. Potential energies are conservative by nature.

Answer from: Quest

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol

b. a hockey puck sliding across the ice

c. a compressed spring

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice is the correct option.

Answer from: Quest

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem. $\begin{aligned} | \vec{v}| & = \sqrt{(\text{2.7 m/s})^2 + (\text{1.2 m/s})^2 } \\ & = 2.954 \text{ m/s} \end{aligned}$ to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.

Other questions on the subject: Physics

Physics, 22.06.2019 04:30, meababy2009ow9ewa

Idon’t quite understand this problem

Answers: 1

continue

Physics, 22.06.2019 05:50, gabigraceberg

High schoolphysics 5+3 pts a neon light consists of a glass tube with metal wires at each end. when connected to a high-voltage source, the gas glows. if a fly lands on the glass tube, what will most likely happen? a) the fly will not feel a shock because the glass conducts any free electrons back into the gas. b) electrons will flow directly from the metal wires along the glass and shock the fly. c) the fly will not feel a shock because the glass insulates it from the electrons in the gas and the metal. d) electrons that are moving through the gas will be conducted through the glass and shock the fly.

Answers: 3

continue

Physics, 22.06.2019 15:50, rosepetals2938

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?

Answers: 1

continue

Physics, 22.06.2019 22:30, ari9425

Compare the patterns of the two waves shown in the image. which statement is true about these waves?

Answers: 1

continue

You know the right answer?

(a) Calculate the kinetic energy, in joules of a 1200 -kg automobile moving at 18 m/s . (b) Convert...