Answer:
* roller skates and ice skates.
* roller coaster
Explanation:
One of the best examples for this situation is when we are skating, in the initial part we must create work with a force, it compensates to move, after this the external force stops working and we continue movements with kinetic energy, if there are some ramps, we can going up, where the kinetic energy is transformed into potential energy and when going down again it is transformed into kinetic energy. This is true for both roller skates and ice skates.
Another example is the roller coaster, in this case the motor creates work to increase the energy of the car by raising it, when it reaches the top the motor is disconnected, and all the movement is carried out with changes in kinetic and potential energy. In the upper part the energy is almost all potential, it only has the kinetic energy necessary to continue the movement and in the lower part it is all kinetic; At the end of the tour, the brakes are applied that bring about the non-conservative forces that decrease the mechanical energy, transforming it into heat.
Answer:
Explanation:you must first make a free body diagram of the block to place all the forces that act on the block there. You will have four forces. The normal force, the weight, the horizontal force in x (which is what they ask to calculate) and the friction force. Then you raise the equations and you clear the values. I attach the solution.
D.) Vertical relationships involve unequal status, while horizontal relationships represent equal status.
HOPE THIS HELPS!
Answer: 26.84 m/s
Explanation:
Given
Original frequency of the horn 
Apparent frequency 
Speed of sound is 
Doppler frequency is
Where,
Insert values
![\Rightarrow 246=228\left[\dfrac{340+v_o}{340-0}\right]\\\\\Rightarrow 366.84=340+v_o\\\Rightarrow v_o=26.8\ m/s](https://tex.z-dn.net/?f=%5CRightarrow%20246%3D228%5Cleft%5B%5Cdfrac%7B340%2Bv_o%7D%7B340-0%7D%5Cright%5D%5C%5C%5C%5C%5CRightarrow%20366.84%3D340%2Bv_o%5C%5C%5CRightarrow%20v_o%3D26.8%5C%20m%2Fs)
Thus, the speed of the car is 
Answer: option 4: A wire that is 2-mm thick and coiled.
Explanation:
The current in each wire is same. The magnetic field due to a current carrying wire increases if the wire is coiled with the more number of turns. A thick wire would cause low resistance to the current. Hence, a 2-mm thick wire which is coiled would produce the strongest magnetic field.
