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- When in air the upward force (upthrust) is negligible / (l) when in water the object experiences an upthrust (1) hence when in water the net downward force is less than when (l) in air (when only the weight acts on the body)
lemass answered the question on January 21, 2019 at 08:28
- A spring supporting a weight of 30N extends by 1.5 cm. Determine the spring constant.(Solved)
A spring supporting a weight of 30N extends by 1.5 cm. Determine the spring constant.
Date posted: January 21, 2019. Answers (1)
- A uniform plank of wood of length 5 m is pivoted at its centre. A girl of mass 32 kg sits at one end of...(Solved)
A uniform plank of wood of length 5 m is pivoted at its centre. A girl of mass 32 kg sits at one end of the plank. Determine how far from the pivot a boy of mass 40 kg should sit in order to balance the plank.
Date posted: January 21, 2019. Answers (1)
- A screen is placed 80cm from an object. A lens is used to produce on the screen an image with a magnification of 3. What...(Solved)
A screen is placed 80cm from an object. A lens is used to produce on the screen an image with a magnification of 3. What is the distance between the object and the lens? Calculate the focal length of that lens.
Date posted: January 21, 2019. Answers (1)
- A bullet is shot vertically upward and rises for a maximum height of 1000 m. What is the initial velocity...(Solved)
A bullet is shot vertically upward and rises for a maximum height of 1000m. What is the initial velocity of the bullet and the total time of flight?
Date posted: January 14, 2019. Answers (1)
- Explain why during anomalous expansion of water, heat transfer is limited to conduction and radiation(Solved)
Explain why during anomalous expansion of water, heat transfer is limited to conduction and radiation.
Date posted: December 30, 2018. Answers (1)
- State a reason why it may not be possible to suck a liquid into your mouth using drinking straw on the surface of the moon(Solved)
State a reason why it may not be possible to suck a liquid into your mouth using drinking straw on the surface of the moon.
Date posted: December 10, 2018. Answers (1)
- State the reason why the speed of the water at the narrow section of a river is higher than at the wider section(Solved)
State the reason why the speed of the water at the narrow section of a river is higher than at the wider section.
Date posted: November 29, 2018. Answers (1)
- Two vertical opposite forces act on a metre rule at the 10cm and 60cm mark respectively. If each of the forces has a magnitude of 2.4N.calculate...(Solved)
Two vertical opposite forces act on a metre rule at the 10 cm and 60 cm mark respectively.if each of the forces has a magnitude of 2.4N. Calculate their moments on the metre rule about the 30 cm mark.
Date posted: November 13, 2018. Answers (1)
- Explain the applications of junction diodes(Solved)
Explain the applications of junction diodes.
Date posted: October 18, 2018. Answers (1)
- Explain the occurrence of forward bias of a p-n junction and reverse bias of a p-n junction(Solved)
Explain the occurrence of forward bias of a p-n junction and reverse bias of a p-n junction.
Date posted: October 18, 2018. Answers (1)
- What are junction diodes?(Solved)
What are junction diodes?
Date posted: October 18, 2018. Answers (1)
- What is an intrinsic semiconductor?(Solved)
What is an intrinsic semiconductor?
Date posted: October 18, 2018. Answers (1)
- Define the following terms (i) Conductors (ii) Insulators (iii) Semiconductors (Solved)
Define the following terms (i) Conductors (ii) Insulators (iii) Semiconductors
Date posted: October 18, 2018. Answers (1)
- Hazards of radioactivity and their precautions(Solved)
Hazards of radioactivity and their precautions
Date posted: October 17, 2018. Answers (1)
- A radioactive element has an initial count rate of 2,400 counts per minute on a scaler. The count rate falls to 300 units per minute...(Solved)
A radioactive element has an initial count rate of 2,400 counts per minute on a scaler. The count rate falls to 300 units per minute in 30 hours, (a) Calculate the half-life of the element (b) If the initial number of atoms in another sample of the same element is 6.0 × 1020, how many atoms will have decayed in 50 hours?
Date posted: October 17, 2018. Answers (1)
- The initial number of atoms in a sample is 5.12 × 1020. If the half-life of the sample is 3.0 seconds, determine the number of...(Solved)
The initial number of atoms in a sample is 5.12 × 1020. If the half-life of the sample is 3.0 seconds, determine the number of atoms that will have decayed after six seconds.
Date posted: October 17, 2018. Answers (1)
- An isotope has a half-life of 576 hours. Complete the following table and show how mass varies with time from an initial mass of 1280...(Solved)
An isotope has a half-life of 576 hours. Complete the following table and show how mass varies with time from an initial mass of 1280 g?
Time (hrs)----576--1152--1728---2304
Mass (g)-------640--x------y-----z
Date posted: October 17, 2018. Answers (1)
- The half-life of a sample of a radioactive substance is 98 minutes. How long does it take for the activity of the sample to reduce...(Solved)
The half-life of a sample of a radioactive substance is 98 minutes. How long does it take for the activity of the sample to reduce to 1/16th of the original value?
Date posted: October 17, 2018. Answers (1)
- State the law of radioactive decay(Solved)
State the law of radioactive decay
Date posted: October 17, 2018. Answers (1)
- Explain ways of detecting nuclear radiation(Solved)
Explain ways of detecting nuclear radiation.
Date posted: October 17, 2018. Answers (1)