A swimmer swims at 5 m/s. How long would it take to swim 5 laps of a 50m pool?

A small glass bead has been charged to +20 nC. A small metal ball bearing 1.0 cm above the bead feels a 0.018 N downward electri

Alla [95]

Answer:

$q=1\times10^{-8}C$

Explanation:

Let the charge on the ball bearing is q.

charge on glass bead, Q = 20 nC = 20 x 10^-9 C

Force between them, F = 0.018 N

Distance between them, d = 1 cm = 0.01 m

By use of Coulomb's law in electrostatics

$F=\frac{KQq}{d^{2}}$

By substituting the values

$0.018=\frac{9\times10^{9}\times20\times10^{-9}q}{0.01^{2}}$

$q=1\times10^{-8}C$

Thus, the charge on the ball bearing is $q=1\times10^{-8}C$

7 0

3 years ago

A lamp is 10% efficient.How much electrical energy must be supplied to the lamp each second if it produces 20 J of light energy

k0ka [10]

If it produces 20J of light energy in a second, then that 20J is the 10% of the supply that becomes useful output.

20 J/s = 10% of Supply

20 J/s = (0.1) x (Supply)

Divide each side by 0.1:

Supply = (20 J/s) / (0.1)

Supply = 200 J/s (200 watts)

========================

Here's something to think about: What could you do to make the lamp more efficient ? Answer: Use it for a heater !

If you use it for a heater, then the HEAT is the 'useful' part, and the light is the part that you really don't care about. Suddenly ... bada-boom ... the lamp is 90% efficient !

6 0

3 years ago

4. An electric iron has a

Licemer1 [7]

Answer:

4.

a) W = 750 J

b) W = 2250 J

c) t = 2 sec

5. Answered in explanation

Explanation:

4.

The formula of power is given as:

P = W/t

where,

P = Power

W = Work Done

t = Time Taken

a)

Here,

P = 750 W

t = 1 sec

W = ?

Therefore,

750 W = W/1 sec

W = 750 J

b)

Here,

P = 750 W

t = 3 sec

W = ?

Therefore,

750 W = W/3 sec

W = (750 W)(3 sec)

W = 2250 J

c)

Here,

P = 750 W

t = ?

W = 1500 J

Therefore,

750 W = 1500 J/t

t = 1500 J/750 W

t = 2 sec

5.

According to Kinetic Particle Theory, the molecules are tightly packed with each other, by strong inter-molecular forces and they can only vibrate at their position. While, molecules or particles in liquids have lesser attractive forces among them. They can move in layers and can take the shape of any container. This is the reason why solid has a definite shape and liquid has none.

6 0

2 years ago

Can someone help me figure out how to find tension in a rope? The question is:

Simora [160]

You are welcome.......