Work done is given by the change in kinetic energy of an object
- The kinetic energy of the shovel, the shrub, and in Robert's movement were changed, therefore, work is done in the given processes,
Reason:
Work is done when the total energy of object is affected by the application of force on the object over a distance
Therefore;
- In option <em>A</em>, pushing the shovel into ground (to dig out the dirt) the requires the application of a force (push) over a distance, (into and out of the ground) therefore work is done
- In option <em>B</em>, picking the shrub up gives it gravitational potential energy, therefore, work is done
- In option <em>C</em>, carrying the shrub to the hole does visible work
- In option <em>D</em>, holding the shrub while lowering it into the hole does work by preventing the shrub from falling randomly
Therefore, <u>work is done in the given processes</u>
Learn more about work-energy theorem here:
brainly.com/question/10063455
Answer:
=118.8 K= 154.2°C
Explanation:
COP_max of carnot heat pump= 
where T_H and T_C are temperatures of hot and cold reservoirs
Also COP=
in the question 
⇒
heat is added directly to be as efficient as via heat pump

and T_H= 24° C= 297 K

on calculating the above equation we get
=118.8 K
the outdoor temperature for efficient addition of heat to interior of home
=118.8 K= 154.2°C
Answer:
= 4.3 × 10 ⁻¹⁴ m
Explanation:
The alpha particle will be deflected when its kinetic energy is equal to the potential energy
Charge of the alpha particle q₁= 2 × 1.6 × 10⁻¹⁹ C = 3.2 × 10⁻¹⁹ C
Charge of the gold nucleus q₂= 79 × 1.6 × 10⁻¹⁹ = 1.264 × 10⁻¹⁷C
Kinetic energy of the alpha particle = 5.28 × 10⁶ × 1.602 × 10⁻¹⁹ J ( 1 eV)
= 8.459 × 10⁻¹³
k electrostatic force constant = 9 × 10⁹ N.m²/c²
Kinetic energy = potential energy = k q₁q₂ / r where r is the closest distance the alpha particle got to the gold nucleus
r = ( 9 × 10⁹ N.m²/c² × 3.2 × 10⁻¹⁹ C × 1.264 × 10⁻¹⁷C) / 8.459 × 10⁻¹³
= 4.3 × 10 ⁻¹⁴ m
Answer: Hopefully 50trillion DNA strands
Answer:

Explanation:
The force of kinetic friction on the block is defined as:

Where
is the coefficient of kinetic friction between the block and the surface and N is the normal force, which is always perpendicular to the surface that the object contacts. So, according to the free body diagram of the block, we have:

Replacing this in the first equation and solving for
:
