Answer:
1. a = -10 m/s²
2. a = 1.8 × 10³ km/h²; s = 0.31 km
Explanation:
1.
Given:
Initial speed (u): 30 m/s
Final speed (v): 0 m/s (rest)
Time elapsed (t): 3.0 s
Asked:
Acceleration (a)
Solution:
We will use the following expression.
a = (v-u)/t = (0 m/s - 30 m/s)/3.0 s = -10 m/s²
Final Answer:
a = -10 m/s²
2.
Given:
Initial speed (u): 50 km/h
Final speed (v): 60 km/h
Time elapsed (t): 20 s
Asked:
(a) Acceleration (a)
(b) Distance traveled (s)
Solution:
(a) First, we will convert the time to hours.
20 s × 1 h/3600 s = 0.0056 h
Then, we will use the following expression.
a = (v-u)/t = (60 km/h - 50 km/h)/0.0056 h = 1.8 × 10³ km/h²
(b) We will use the following expression.
s = u × t + 1/2 × a × t²
s = 50 km/h × 0.0056 h + 1/2 × 1.8 × 10³ km/h² × (0.0056 h)² = 0.31 km
Final Answer:
a = 1.8 × 10³ km/h²
s = 0.31 km
To calculate the number of moles, the equation is mass of substance divided by the molar mass of substance.
Molar mass of Fe2O3 is the relative atomic mas of all the elements from the substance added up, which makes 55.845x2 + 16.0 x3 = 159.69g mol-1
So the number of moles is
545g / 159.69gmol-1
=3.41 mol (corrected to 3 sig. fig.)
Answer:
(D) Water from streams and rivers carry salt to the ocean
Explanation:
Hope this helps!
Answer:
Chemistry is the study of matter , its properties,how and why substance combine or separate to form other substance.
It's uses are
1) It is used in health care and beauty
2) Industries and transportation
3) Agriculture, science and technology
4) Cooking , cleaning, medicines etc
Answer:
200 grams is the mass of 15% of the solution of lime that is formed by dissolving 30g of calcium hydroxide in water.
Explanation:
Mass of solution = M
Mass percentage of the solution of lime = 15%
Mass of lime or calcium hydroxide = m = 30 g
The Formula of mass percentage is given as :
On substituting the values in ab above formula :
200 grams is the mass of 15% of the solution of lime that is formed by dissolving 30g of calcium hydroxide in water.
