Answer:
5.16 m/s
Explanation:
mass of car, m1 = 1689 kg
mass of truck, m2 = 2000 kg
Velocity of truck after collision, v2 = 17 km/h = 4.72 m/s
Let the initial velocity of car is u1.
initial velocity of truck, v1 = 0
velocity of car after collision, v1 = ?
Use conservation of momentum
m1 x u1 + m2 x u2 = m1 x v1 + m2 x v2
1689 x u1 + 2000 x 0 = 1689 x v1 + 2000 x 4.72
1689 u1 = 1689 v1 + 9444.4 .... (1)
As the collision is elastic, so coefficient of restitution is 1.
Use the formula for the coefficient of restitution.
e = 1
v1 - 4.72 = 0 - u1
v1 = 4.72 - u1
Substitute the value of v1 in equation (1)
1689 u1 = 1689 (4.72 - u1) + 9444.44
1689 u1 = 7972.08 - 1689 u1 + 9444.44
3378 u1 = 17416.52
u1 = 5.16 m/s
Thus, the speed of car before collision is 5.16 m/s.
Answer:
The frictional force needed to overcome the cart is 4.83N
Explanation:
The frictional force can be obtained using the following formula:
where is the coefficient of friction = 0.02
R = Normal reaction of the load = =
=
Now that we have the necessary parameters that we can place into the equation, we can now go ahead and make our substitutions, to get the value of F.
F = 4.83 N
Hence, the frictional force needed to overcome the cart is 4.83N
Answer:
The bomb will remain in air for <u>17.5 s</u> before hitting the ground.
Explanation:
Given:
Initial vertical height is,
Initial horizontal velocity is,
Initial vertical velocity is,
Let the time taken by the bomb to reach the ground be 't'.
So, consider the equation of motion of the bomb in the vertical direction.
The displacement of the bomb vertically is
Acceleration in the vertical direction is due to gravity,
Therefore, the displacement of the bomb is given as:
So, the bomb will remain in air for 17.5 s before hitting the ground.
You are on an aluminum ladder that is standing on the ground, trying to fix an electrical connection with a metal screwdriver having a metal handle. Your body is wet because you are sweating from the exertion; therefore, it has a resistance of 1.60 kΩ .
(a) If you accidentally touch the "hot" wire connected to the 120 V line, how much current will pass through your body?
(b) How much electrical power is delivered to your body?
<h2>Answer:</h2>(a) 0.075A
(b) 9W
<h2>Explanation:</h2>The voltage (V) passing across or supplied to a body is directly proportional to the current (I) flowing through the body as stated by Ohm's law. i.e
V ∝ I
=> V = I x R ----------------------(i)
Where;
R = constant of proportionality called resistance of the body
(a) As stated in the question;
The body is wet and thus will conduct electricity and has the following;
V = voltage supplied = 120V
R = resistance of the wet body = 1.60kΩ = 1.6 x 1000Ω = 1600Ω
Substitute these values into equation(i) as follows;
120 = I x 1600
Solve for I;
I =
I = 0.075A
Therefore the amount of current that will pass through your body is 0.075A
(b) Electrical power(P), which is commonly measured in Watts(W), delivered to a body is the product of the current(I) and voltage (V) supplied to the body. i.e
P = I x V ---------------------(ii)
Where;
I = 0.075A [as calculated above]
V = 120V [given in the question]
Substitute these values into equation (ii) as follows;
P = 0.075 x 120
P = 9W
Therefore, the electric power delivered to your body is 9W
Answer:
Explanation:
We are given that
Initial velocity=u=18ft/s
Final velocity,v=38ft/s
Time=t=3 s
We have to find the average acceleration over that 3 s period.
We know that
Average acceleration,a=
Using the formula
Average acceleration,a=
Average acceleration,a=
Average acceleration,a=
Hence, the average acceleration=