Answer:
Option A. 39.2 m/s
Explanation:
From the question given above, the following data were obtained:
Initial velocity (u) = 0 m/s
Acceleration due to gravity (g) = 9.8 m/s²
Time (t) = 4 s
Final velocity (v) =?
v = u + gt
Since the initial velocity (u) is 0, the above equation becomes:
v = gt
Thus, inputting the value of g and t, we can obtain the value of v as shown below:
v = 9.8 × 4
v = 39.2 m/s
Therefore, the velocity of the ball at 4 s is 39.2 m/s.
I think the answer may be the letter B
Answer:
See explanations below
Explanation:
Power = Workdone/Time
Power of washer = 450watts
Time used to clean the clothes = 1hour = 3600secs
Energy used to clean a load of clothes in 1 hour of
washing = 450/3600
Energy used to clean a load of clothes in 1 hour of
washing = 0.125Joules
For drying;
Energy = 3000/1.5*3600
Energy = 3000/5400
Energy = 0.556Joules
Hence the energy in washing id 0.556Joules
Answer:
Because the uncontrolled and unreasonable use of energy resources in the past few decades has led to the depletion of conventional type of resources. Although, measures are taken at the government levels to control the energy consumption, these attempts only meet with little success. Public awareness is the only way to successfully deal with this problem.
Explanation:
Answer:
C. The wheel with spokes has about twice the KE.
Explanation:
Given that
Mass , radius and the angular speed for both the wheels are same.
radius = r
Mass = m
Angular speed = ω
The angular kinetic energy KE given as

I=Moment of inertia for wheels
Wheel made of spokes
I₁ = m r²
Wheel like a disk
I₂ = 0.5 m r²
Now by comparing kinetic energy



KE₁= 2 KE₂
Therefore answer is C.