Work = Force * distance
W = Fd
Given F = 500 N, d = 10 m
W = (500)(10)
W = 5000 J
The work done is 500 Joules. The time of 4 s is irrelevant in this case.
Answer:
Due to potential difference (elaborated in explanation)
Explanation:
When a bird sits on a power line, its whole body is in contact with the power line. It does not have any contact with the ground or anything at a lower potential. Hence, the current does not flow through the bird's body, because there is no potential difference available as a driving force.
Now, when a person touches the power line his hand is at a higher potential provided by the power line, while the rest of his body is connected to the ground, usually through legs. The current always looks for a path from high potential to low potential. Therefore, the body of the person serves as the path for the current. Heavy current flows through the body and the person dies within split seconds.
Answer:
a) 103.32 m
b) 9.18 s
Explanation:
a) Let's use the knowledge that at the top of its trajectory, the baseball will have a final velocity of 0 m/s.
The acceleration due to gravity is -9.8 m/s², assuming the upwards direction is positive and the downwards direction is negative.
The initial velocity of the baseball is 45 m/s.
We are trying to find the vertical displacement of the baseball, Δx, and we have the variables v, a, and v₀.
Find the constant acceleration equation that contains all four of these variables:
Substitute the known values into the equation.
- (0)² = (45)² + 2(-9.8)Δx
- 0 = 2025 - 19.6Δx
- -2025 = -19.6Δx
- Δx = 103.32
The maximum height of the ball before it falls back down is 103.32 m.
b) Now we want to solve for time t. Find a constant acceleration equation that contains three known variables.
Substitute known values into this equation.
- 0 = 45 + (-9.8)t
- -45 = -9.8t
- t = 4.59183673
Remember that this is only half of the baseball's flight since we are using the final velocity for when the ball is halfway through its trajectory.
To solve for the total time the baseball is in the air, double the time t we solved for.
The baseball is in the air for 9.18 s.
Answer:
11.16 J
Explanation:
Elastic energy (E) stored in the tendon is given by 1/2ke^2
SPRINTERS
k = 31N/mm = 31N/mm × 1000mm/1m = 31,000N/m
e = 41mm = 41mm × 1m/1000mm = 0.041m
E = 1/2 × 31,000 × 0.041^2 = 26.06J
NON-ATHLETES
k = 31,000N/m
e = 31mm = 31mm × 1m/1000 = 0.031m
E = 1/2 × 31,000 × 0.031^2 = 14.90 J
Difference = 26.06 J - 14.90 J = 11.16 J
Answer:
11. 5 N to the left.
12. 10 N to the right.
Explanation:
11. Determination of the net force.
Force in the left direction (Fₗ) = 10 N
Force in the right direction (Fᵣ) = 5 N
Net force (Fₙ) =?
The net force can be obtained as follow:
Fₙ = Fₗ – Fᵣ (Since the forces act in opposite direction)
Fₙ = 10 – 5
Fₙ = 5 N to left
Thus, the net force is 5 N to the left.
12. Determination of the net force.
Force in the right direction 1 (Fᵣ₁) = 5 N
Force in the right direction 2 (Fᵣ₂) = 5 N
Net force (Fₙ) =?
The net force can be obtained as follow:
Fₙ = Fᵣ₁ + Fᵣ₂ (Since the forces act in the same direction)
Fₙ = 5 + 5
Fₙ = 10 N to the right
Thus, the net force is 10 N to the right.
