Answer:
the work done by the lawnmower is 236.14 J.
Explanation:
Given;
power exerted by the lawnmower engine, P = 19 hp
time in which the power was exerted, t = 1 minute = 60 s.
1 hp = 745.7 watts
The work done by the lawnmower is calculated as follows;

Therefore, the work done by the lawnmower is 236.14 J.
The size of the force varies inversely as the square of the distance between the two charges. Therefore, if the distance between the two charges is doubled, the attraction or repulsion becomes weaker, decreasing to one-fourth of the original value.
Answer:
371.2 mm
Explanation:
The Balmer series of spectral lines is obtained from the formula
1/λ = R(1/2² -1/n²) where λ = wavelength, R = Rydberg's constant = 1.097 × 10⁷ m⁻¹
when n = 15
1/λ = 1.097 × 10⁷ m⁻¹(1/2² -1/15²)
= 1.097 × 10⁷ m⁻¹(1/4 -1/225)
= 1.097 × 10⁷ m⁻¹(0.25 - 0.0044)
= 1.097 × 10⁷ m⁻¹ 0.245556
= 2.693 10⁶ m⁻¹
So,
λ = 1/2.693 10⁶ m⁻¹
= 0.3712 10⁻⁶ m
= 371.2 mm
Answer:an open flame
Explanation:
Flammable materials like alcohol should never be dispensed or used near an open flame