Answer:
4.2s
Explanation:
Given parameters:
Power = 2190W
Mass of box = 1.47 x 10⁴g
distance = 6.34 x 10⁴mm
Unknown:
Time = ?
Solution:
Power is the rate at which work is done;
Mathematically;
Power =
Time =
Work done = weight x height
convert mass to kg;
100g = 1kg;
1.47 x 10⁴g = 14.7kg
convert the height to m;
1000mm = 1m
6.34 x 10⁴mm gives 63.4m
Work done = 14.7 x 9.8 x 63.4 = 9133.4J
Time taken =
= 4.2s
Answer:
d) shortening the string
Explanation:
Time period of a pendulum clock is dependent on two factors namely:length and acceleration due to gravity.
When a clock loses time, the time period of the pendulum clock increases.
This however can be corrected by decreasing the length of the pendulum.The time period of the pendulum clock is not dependent on the mass of the bob. The time period of the pendulum clock can be corrected only by changing the length of the pendulum string.
Answer: Option (d) is correct.
Explanation:
Given, 1,152 British thermal units
1 British thermal unit = 1055.06 joules
So, in 1,152 British thermal units there will be :

Hence, from the given options the closest answer is of option (d). So, option (d) is correct.
Power = Work done/Time taken
So, keeping this in mind,we can solve it as follows:
= 700/3.1
= 7000/31
= 225.80 W