Answer:
32000 N
Explanation:
From the question given above, the following data were obtained:
Initial velocity (u) = 40 m/s
Distance (s) = 10 m
Final velocity (v) = 0 m/s
Mass (m) of car = 400 Kg
Force (F) =?
Next, we shall determine the acceleration of the the car. This can be obtained as follow:
Initial velocity (u) = 40 m/s
Distance (s) = 10 m
Final velocity (v) = 0 m/s
Acceleration (a) =?
v² = u² + 2as
0² = 40² + (2 × a × 10)
0 = 1600 + 20a
Collect like terms
0 – 1600 = 20a
–1600 = 20a
Divide both side by –1600
a = –1600 / 20
a = –80 m/s²
The negative sign indicate that the car is decelerating i.e coming to rest.
Finally, we shall determine the force needed to stop the car. This can be obtained as follow:
Mass (m) of car = 400 Kg
Acceleration (a) = –80 m/s²
Force (F) =?
F = ma
F = 400 × –80
F = – 32000 N
NOTE: The negative sign indicate that the force is in opposite direction to the motion of the car.
The efficiency of an ideal Carnot heat engine can be written as:
where
is the temperature of the cold region
is the temperature of the hot region
For the engine in our problem, we have
and
, so the efficiency is
Capable of being reversed or of reversing: as a : capable of going through a series of actions (as changes) either backward or forward
Example : water ----> ice
melts into water again<span />
The force of gravity on earth is towards the center of it
In the downward direction
The spring starts out 22 cm long with nothing hanging on it.
Hanging 35 newtons of weight on it stretches the spring 1 meter.
Ellen is going to hang 250 grams of mass on the spring.
What's the weight of 250 grams of mass ?
Weight = (mass) x (acceleration of gravity in the place where the mass is) .
On Earth, the acceleration of gravity is 9.8 m/s² .
250 grams is 0.25 of a kilogram.
Weight of 250 grams = (0.25 kilogram) x (9.8 m/s²)
= (0.25 x 9.8) kg-m/s²
= 2.45 newtons .
2.45 newtons of weight is (2.45 / 35) of 35 newtons,
so it'll stretch the spring (2.45 / 35) of a meter.
2.45/35 = 0.07 of a meter = 7 centimeters.
The spring was 22 cm long with nothing hanging on it,
and the 250-gm weight stretched it 7 cm.
So with the weight hanging on it, it's (22 + 7) = 29 cm long.
