Answer:
A heat engine is a device that converts internal energy into work. Internal energy is increased by the addition of heat. The efficiency of a heat engine is a measurement of how efficiently it works. Efficiency compares the amount of useful energy extracted from a process to the total energy input. The heat engine will be more efficient if the percentage is higher.
Explanation:
Answer
given,
before collision
mass of car A = m_a = 1300 kg
velocity of car A = v_a = 35 mph
mass of car B = m_b= 1000 kg
velocity of car B = v_b = 25 mph
after collision
V_a = 30 mph
V_b = 31.5 mph
Initial momentum



final momentum



here initial momentum is equal to the final momentum of the car.
hence, momentum is conserved in the collision.
Answer:
The velocity with which the jumper strike the mat in the landing area is 6.26 m/s.
Explanation:
It is given that,
A high jumper jumps over a bar that is 2 m above the mat, h = 2 m
We need to find the velocity with which the jumper strike the mat in the landing area. It is a case of conservation of energy. let v is the velocity. it is given by :

g is acceleration due to gravity

v = 6.26 m/s
So, the velocity with which the jumper strike the mat in the landing area is 6.26 m/s. Hence, this is the required solution.
Answer: A, C and D
Explanation:
Interference occurs when two waves superimpose to form a wave having a smaller or larger amplitude.
Constructive interference is said to occur when two waves superimpose to produce a wave having larger amplitude. It occurs for the waves having phase difference of multiple of 2π. On the other hand, destructive interference occurs for the waves having phase difference π, 3π, ..and so on.
In the given picture, the bright regions represent constructive interference where as the dark ones between them represent destructive interference. Thus, the correct letters representing constructive interference are: A, C and D.
The collision of car 2 is more violent (because more impulse is exerted)
Explanation:
The collision which is more violent is the one in which more impulse is exchanged.
The impulse exerted by each car on the wall is equal to the change in momentum of the car:

where
m is the mass of the car
is the change in velocity
For the car 1,
m = 1000 kg
(the sign is negative because the velocity of the car has changed from 100 km/h to 0 km/h)
So the magnitude of the impulse of car 1 is

For the car 2,
m = 1200 kg

So the magnitude of the impulse of car 2 is

So, car 2 exerts a larger impulse, therefore its impact is more violent.
Learn more about impulse and change in momentum:
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