Complete Question
The complete question is shown on the first and second uploaded image
Answer:
The velocity is
Explanation:
The kinetic energy of the 9 kg can be determined by these expression
Kinetic energy of 9 kg block = initial energy stored - energy lost as a result of friction
Now to obtain the initial energy stored
Let U denote the initial energy stored and

Where x is the length the spring is displaced
k is the force constant of the string


Now referring to the formula above
i.e Kinetic energy of 9 kg block = initial energy stored - energy lost as a result of friction



and we are told that coefficient of friction = 0.4 and the mass is 9 kg ,the acceleration due to gravity
this displacement length of spring = 0.6
Therefore 
Newton's 2nd law of motion: Force = (mass) x (acceleration)
Divide each side by (mass) : Acceleration = (force) / (mass)
Acceleration of the truck = (4,200 N) / (2,000 kg) = 2.1 m/s²
Answer:
D. Friction and air resistance created heat on his trip up the hill.
Explanation:
Energy transformation from one form to another is not 100% efficient. This is the postulate of the first law of thermodynamics.
Most of the energy transformation is not purely 100%.
When energy is transformed, some are usually wasted.
- In this case, in moving from bottom up, Superman produced some heat and encountered air resistance.
- To reach the top, he must have overcome the resistance and produce enough heat to power him through.
- This reduces the amount of potential energy that should have been the same as the kinetic energy down below.
The Kinetic energy of an object is given by:

Where m is the mass of the object (kg) and v is the velocity of the object (ms-1)
Substituting in:

Therefore the Kinetic energy of the object is
1.35MJ
The pressure inside the container will be <u>9.39×10⁴Pa</u>
At constant volume, the pressure in a container is directly proportional to its absolute temperature.
If air in a container is sealed at 20⁰C at a pressure equal to the atmospheric pressure and cooled to 2.00⁰C, the pressure inside the container falls.
Convert the temperature in Celsius to Kelvin.

Use the expression for the pressure law.

Substitute 100,000 Pa for P₁, 293.16 K for T₁ and 275.15K for T₂.

The pressure in the container (correct to 2 sf) is <u>9.39×10⁴Pa</u>