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3 years ago

Someone help please i need to finish this

Physics

1 answer:

Tom [10]3 years ago

6 0

Answer:

4th answer

Explanation:

The gradient of a distance-time graph gives the speed.

gradient = distance / time = speed

Here, the gradient is a constant till 30s. So it has travelled at a constant speed. It means it had not accelarated till 30s. and has stopped moving at 30s.

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The light from the Sun heats a metal surface

Nina [5.8K]

This is called Conduction.

4 0

3 years ago

A student decides to move a box of books into her dormitory room by pulling on a rope attached to the box. She pulls with a forc

____ [38]

Answer:

Part a)

$a = 0.36 m/s^2$

Part b)

$a = -1.29 m/s^2$

Explanation:

Force applied by the student on the box is 80 N at an angle of 25 degree

so here two components of the force on the box is given as

$F_x = Fcos25$

$F_x = 80 cos25 = 72.5 N$

$F_y = Fsin25$

$F_y = 80 sin25 = 33.8 N$

now in vertical direction we can use force balance for the box to find the normal force on it

$F_n + F_y = mg$

$F_n = (25)(9.81) - 33.8$

$F_n = 211.45 N$

now kinetic friction on the box opposite to applied force due to rough floor is given as

$F_k = \mu F_n$

$F_k = (0.300)(211.45) = 63.44 N$

now the net force on the box in forward direction is given as

$F_{net} = F_x - F_k$

$F_{net} = 72.5 - 63.44 = 9.065 N$

now the acceleration of the box is given as

$a = \frac{F_{net}}{m}$

$a = \frac{9.065}{25} = 0.36 m/s^2$

Part b)

when box is pulled up along the inclined surface of angle 10 degree

now the two components of the force will be same along the inclined and perpendicular to inclined plane

$F_x = 72.5 N$

$F_y = 33.8 N$

now force balance perpendicular to inclined plane is given as

$F_n + F_y = mgcos\theta$

$F_n = (25)(9.81)cos10 - 33.8 = 207.7 N$

now the friction force opposite to the motion on the box is given as

$f_k = \mu F_n$

$f_k = (0.300)(207.7) = 62.3 N$

now the net pulling force along the inclined plane is given as

$F_{net} = F_x - F_k - mgsin10$

$F_{net} = 72.5 - 62.3 - (25)(9.81)sin10$

$F_{net} = -32.38 N$

now the box will decelerate and it is given as

$a = \frac{F_{net}}{m}$

$a = \frac{-32.38}{25} = -1.29 m/s^2$

7 0

4 years ago

Light, dry snow is called powder. Skiing on a powder day is different than skiing on a day when the snow is wet and heavy. When

kramer

Answer:

Explanation:

Given:

- Acceleration a_dry = 0.4*a_wet

- initial velocity V_i

Find:

By how much does time taken to stop of dry snow differ from time taken to stop on wet snow?

Solution:

- Time taken to stop on wet snow t_wet:

V_f = V_i + a_wet * t_wet

t_wet = - a_wet / V_i

- Time taken to stop on wet snow t_wet:

V_f = V_i + a_dry * t_dry

t_dry = - a_dry / V_i

- Difference in t_wet and t_dry:

t_dry - t_wet = - a_dry / V_i + a_wet / V_i

dt = (a_wet - a_dry) / V_i

dt = (a_wet - 0.4*a_wet) V_i

dt = 0.6*a_wet / V_i

3 0

3 years ago

How do subatomic particles create net charge on objects?

Andru [333]

Answer:

If an object has more protons than electron then the net charge on the object is positive but if it has more electrons than protons the net charge on the object is negative. The object is electrically neutral if the number of protons is equal to the number of electrons.

Explanation:

Atom is composed of different subatomic particles . The 3 major subatomic particles are proton , neutron and electrons. The proton and the neutron is concentrated in the nucleus of an atom. The nucleus forms the dense core of an atom. The protons are positively charged while the electrons are negatively charged .The neutrons are neutrally charged. The electrons forms a cloud around the nucleus of an atom.

The net charge is defined as sum of the charges on an object. The 2 electric charges available are positive or negative charges. The proton are positive while the electron are negative. Although the mass of the proton is greater than the electron but the magnitude of their charges are equal . If an object has more protons than electron then the net charge on the object is positive but if it has more electrons than protons the net charge on the object is negative. The object is electrically neutral if the number of protons is equal to the number of electrons.

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3 years ago

Why are boiling chips added to the distillation flask?

Vedmedyk [2.9K]

Answer:

Boiling chips should be placed in the distillation flask for two reasons: they will prevent superheating of the liquid being distilled and they will cause a more controlled boil, eliminating the possibility that the liquid in the distillation flask will bump into the condenser.

5 0

3 years ago