Answer:
-2.33 m/s²
Explanation:
The computation of the skateboarder’s acceleration is shown below;
Acceleration means the change in velocity per unit with respect to time.
In the given case, the initial velocity is 7 m/s.
As in the question it is mentioned that it comes to a stop, so the final velocity would be zero.
And, The time elapsed is 3 seconds.
Now the following equation should be used
a = (v,final - v,initial) ÷ t
= (0 - 7)/3
= -2.33 m/s²
Write the SI unit of time and temperature
Answer:
The SI unit of time is second (s) and temperature is Kelvin (K)
Explanation:
hope it is helpful to you
it took 500 n of force to push a car 4 meters. how much work was done?
Answer:
2000J
Explanation:
The formula for work is W=Force x Distance
W=FxD
W=500N x 4m
W=2,000 Joules
an airplane has a maximum velocity of 160km/h in still air. calculate its maximum velocity when it travels in air with a crosswind of 30km/h
Answer:
Velocity can be directly added or subtracted.
For example, if a boat has a velocity V in still water.
And now you put the boat in a river with a current that has a velocity V'
The total velocity of the boat in that river is just the addition of these two velocities.
Velocity in the river = V + V'
Where the only tricky part is that the velocity is a vector, so you need to take in account the directions of each vector.
In this case, we have a plane with a maximum velocity of 160km, let's assume a direction for this velocity, let's say that is in the positive x-direction.
Then we can write the velocity in the vector form:
velocity = (vel in x-axis, vel in y-axis)
The velocity of the plane can be written as:
v = (160km/h, 0)
Now we add a crosswind of 30km/h
crosswind means that it is perpendicular, then it acts on the y-axis.
Then the total velocity of the plane will be:
velocity = (160km/h, 0) + (0, 30km/h)
velocity = (160km/h, 30km/h)
Now you can compute the total velocity of the airplane as the module of that vector.
Remember that for a vector (x, y) the module is:
mod = √(x^2 + y^2)
Then the module of the velocity is:
v = √( (160km/h)^2 + (30km/h)^2) = 162.8 km/h
Which is a property of every
mixture?
If it is known that a motor battery has an input voltage of 12V and a capacity of 6 Ah, how much power and resistor value is required to turn on 8 lamps with a parallel circuit, with the specifications of each lamp having a maximum voltage of 3V and an electric current of 140 mA? How long did all the lights go on until they off?
Answer:
Part A
The power to turn on the lamp, ∑P = 3.36 W
Part B
The Resistor required is approximately 8.04 Ohms
Part C
The time for all the lights to go out is approximately 21.43 hours
Explanation:
The input voltage of the motor battery , V = 12 V
The capacity of the battery, Q = 6 Ah
The number of lamps in parallel = 8 lamps
The maximum voltage of each lamp, = 3 V
The electric current in each lamp = 140 mA
The energy available in a battery, E = Q × V
For the battery, we have;
E = 6 Ah × 12 V = 72 Wh
The energy available in a battery, E = 72 Wh
Part A
The power used by the lamps, [tex]P_i[/tex] = [tex]I_i[/tex] × [tex]V_i[/tex]
∴ The total power used by the lamp, ∑P = 8 × 0.14 A × 3 V = 3.36 W
The power to turn on the lamp, ∑P = 3.36 W
Part B
The resistance required, is given as follows;
Resistor required = (Battery voltage - Lamp voltage)/(The sum of bulb current)
∴ Resistor required = (12 V - 3 V)/(8 × 0.14 A)
The Resistor required = 8.03571429 Ohms
The Resistor required ≈ 8.04 Ohms
Part C
The time for all the lights to go out = The time for the lamps to use all the power available in the battery
The time for all the lights to go out, t = E/∑P
∴ t = 72 Wh/(3.36 W) = 21.4285714 h
∴ The time for all the lights to go out, t ≈ 21.43 h
The time for all the lights to go out = The time for the lamps to use all the power available in the battery = t ≈ 21.43 h
∴ The time for all the lights to go out ≈ 21.43 hours.
What is meant by uniform motion ? Write with an example.
Answer:
This type of motion is defined as the motion of an object in which the object travels in a straight line and its velocity remains constant along that line as it covers equal distances in equal intervals of time, irrespective of the duration of the time.
Explanation:
In Physics, uniform motion is defined as the motion, wherein the velocity of the body travelling in a straight line remains the same. When the distance travelled by a moving thing, is same at several time intervals, regardless of the time length, the motion is said to be uniform motion.