Answer : The correct option is, (D) A machine does 400 joules of work in 5 seconds.
Explanation :
Power : It is defined a the rate of doing work per unit time.
Formula used :
where,
P = power
w = work done
t = time
Now we have to determine the rate of power for the following options.
(A) A machine does 200 joules of work in 10 seconds.
(B) A machine does 400 joules of work in 10 seconds.
(C) A machine does 200 joules of work in 5 seconds.
(D) A machine does 400 joules of work in 5 seconds.
From this we conclude that, a machine does 400 joules of work in 5 seconds has the highest rate of power.
Hence, the correct option is, (D)
Answer: 2.13 × 10⁻⁷ N
Explanation:
Gravitational force exists between any two bodies having mass.
Force of gravity is given by:
It is given that, mass of newborn baby is M = 2.50 kg
Mass of the doctor, m = 80.0 kg
Distance between the two, r = 0.250 m
Gravitational constant, G = 6.67 × 10⁻¹¹ N m²/kg²
⇒F = (6.67 × 10⁻¹¹ N m²/kg² × 2.50 kg × 80.0 kg )÷ (0.250 m)² = 2.13 × 10⁻⁷ N
Thus, the force of gravity between new born baby and doctor is 2.13 × 10⁻⁷ N.