Answer:
7revolutions
Explanation:
Given parameters:
Initial revolution = 250rpm
Final revolution = 150rpm
Time = 4.2s
Unknown:
Number of revolutions that occur at this time = ?
Solution:
To solve this problem;
let us find the change in revolution = 250rpm - 150rpm = 100rpm
Convert the time to seconds;
60s makes 1 minute
4.2s will make 
= 0.07min
So;
The number of revolutions at this time = 100rpm x 0.07min
= 7revolutions
The answer is A because it describes both toy cars
Answer:
2274 J/kg ∙ K
Explanation:
The complete statement of the question is :
A lab assistant drops a 400.0-g piece of metal at 100.0°C into a 100.0-g aluminum cup containing 500.0 g of water at 15 °C. In a few minutes, she measures the final temperature of the system to be 40.0°C. What is the specific heat of the 400.0-g piece of metal, assuming that no significant heat is exchanged with the surroundings? The specific heat of this aluminum is 900.0 J/kg ∙ K and that of water is 4186 J/kg ∙ K.
= mass of metal = 400 g
= specific heat of metal = ?
= initial temperature of metal = 100 °C
= mass of aluminum cup = 100 g
= specific heat of aluminum cup = 900.0 J/kg ∙ K
= initial temperature of aluminum cup = 15 °C
= mass of water = 500 g
= specific heat of water = 4186 J/kg ∙ K
= initial temperature of water = 15 °C
= Final equilibrium temperature = 40 °C
Using conservation of energy
heat lost by metal = heat gained by aluminum cup + heat gained by water
I dont know if you mean lead instead of lean .
anyway i think <u>gamma rays</u> will penetrate further
this is because gamma rays are very penetrating , they have a shorter wave lenght than X-rays because the energy which produced them is greater .
Although both are similar but X-rays will become weaker and less penetrating when passing through a block of lead unlike the gamma rays eventhough it might reduse their intensity > but both will never stop ! .
This is a hard question!! 'cause both are similar but as i said i think gamma rays will penetrate further
An Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.
I hope this helped you with your problem.
