part a)
path of the cyclist consist of three parts
during the first part, she rides for 22 minutes at an average speed of 7.2 m/s. during the second part, she rides for 36 minutes at an average speed of 5.1 m/s. finally, during the third part, she rides for 8.0 minutes at an average speed of 13 m/s.
total distance in first part
total distance in second part
total distance in third part
so total distance would be
part b)
average velocity is given as
so average velocity is 6.76 m/s
Answer:
W = 600 J
Explanation:
We have,
According to attached figure,
Height of the inclined plane is 60 m
Force acting on the block is 10 N
It is required to find the work must be done against gravity to move it to the top of the incline. The work done is given by :
W = mgh
or
So, the work done against the gravity is 600 J.
Answer:
B) The car at point C has less kinetic energy than the car at point B.
Explanation:
We have two types of energy involved in this situation:
- Gravitational potential energy: this is the energy related to the heigth of the car, and it is given by , where m is the mass of the car, g is the gravitational acceleration, and h is the heigth of the car. The potential energy is higher when the car is located higher above the ground.
- Kinetic energy: this is the energy due to the motion of the car, and it is given by , where m is the mass of the car and v is its speed. The kinetic energy is higher when the speed of the car is higher.
- The law of conservation of energy states that the total mechanical energy of the car (sum of potential energy and kinetic energy: ) is constant). This implies that when the car is at a higher point, the kinetic energy is less (because U is larger, so K must be smaller), while when the car is at a lower point, the kinetic energy is larger.
- Based on what we have written so far, we can conclude that the correct statement is:
B) The car at point C has less kinetic energy than the car at point B.
Because the car at point C is located at a higher point than point B, so the car at point C has larger potential energy than at point B, which implies that car at point C has less kinetic energy than the car at point B.