Answer:
The initial velocity of the ball is <u>39.2 m/s in the upward direction.</u>
Explanation:
Given:
Upward direction is positive. So, downward direction is negative.
Tota time the ball remains in air (t) = 8.0 s
Net displacement of the ball (S) = Final position - Initial position = 0 m
Acceleration of the ball is due to gravity. So, 
(Acting down)
Now, let the initial velocity be 'u' m/s.
From Newton's equation of motion, we have:
Plug in the given values and solve for 'u'. This gives,
Therefore, the initial velocity of the ball is 39.2 m/s in the upward direction.
Answer:
Explanation:
Regardless of the initial velocity of the pebble, the acceleration of the pebble is equal to the gravitational acceleration which is equal to 9.8 m/s2 towards downwards direction.
This can be shown by Newton's Second Law. According to the law, the net force applied on an object is equal to mass times acceleration of that object.
During the downward motion, the only force acting on the pebble is the gravitational force, hence its acceleration is equal to gravitational acceleration.
Answer:
yes it was a constant speed and the car traveled 10 meters in 20 seconds.
Explanation:
Answer: 52%
Explanation:
1W = 1 J/s
motor input is 10000 J/s
Potential energy change
PE = 955(9.81)(25.0) = 234,213.75
power needed to change the PE in that time
P = 234,213.75/ 45 = 5,204.75 Watts
motor is 5204.75 / 10000 = 0.520475 or 52% efficient
Answer:
=8.0 Watts
Explanation:
Power is a ratio of work done over time. The power in an electric circuit is calculated using the following formula:
P=I²R
P is power, I is current, R is resistance
Therefore, Power= 4²ₓ 0.5Ω
=8.0 Watts
