Answer:
The atomic number is the number of protons in an atom of an element. In our example, krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus.
Explanation:
Answer:
momentum = 30 kg m/s
Explanation:
momentum (p) = mass (m) × velocity (v)
so,
=》

=》

=》

Answer:
103.5 meters
Explanation:
Given that a stunt person has to jump from a bridge and land on a boat in the water 22.5 m below. The boat is cruising at a constant velocity of 48.3 m/s towards the bridge. The stunt person will jump up at 6.45 m/s as they leave the bridge.
The time the person will jump to a certain spot under the bridge can be calculated by using the formula below:
h = Ut + 1/2gt^2
since the person will fall under gravity, g = 9.8 m/s^2
Also, let assume that the person jump from rest, then, U = 0
Substitute h, U and g into the formula above
22.5 = 1/2 * 9.8 * t^2
22.5 = 4.9t^2
22.5 = 4.9t^2
t^2 = 22.5/4.9
t^2 = 4.59
t = 
t = 2.143 seconds
From definition of speed,
speed = distance /time
Given that the boat is cruising at a constant velocity of 48.3 m/s towards the bridge, substitute the speed and the time to get the distance.
48.3 = distance / 2.143
distance = 48.3 * 2.143
distance = 103.5 m
Therefore, the boat should be 103.5m away from the bridge at the moment the stunt person jumps?
Answer:
Rate of energy loss by radiation is 28.31 Watt
Explanation:
Given that;
m = 30 kg
power p = 12 W
emissivity e = 0.97
Surface Area A = 0.56 m²
outside of the penguin's body T = −22°C
surroundings Temperature Ts = -38°C
the rate of energy loss by radiation = ?
Now, using Stefan-Boltzmann law;
P = σeA [ T⁴ - Ts⁴ ]
Stefan's constant σ = 5.67 × 10⁻⁸
so we substitute
P = 5.67 × 10⁻⁸ × 0.97 × 0.56 [ (-22 + 273 k)⁴ - (-38 + 273 k )⁴]
= 3.079944 × 10⁻⁸ [ 919325376]
= 28.31 Watt
the rate of energy loss by radiation is 28.31 Watt