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musickatia [10]
3 years ago
12

3. An athlete makes a long jump and follows a projectile motion. Air resistance is negligible. Which one of the following statem

ents is true about the athlete? (a) "The athlete has a constant hanzontal und vertical velocities. (h) The athlete han a constant horizontal velocity anil constant downward acceleration ic) The athlete has a constant upward acceleration followed by a constant downward acceleration d) The athlete has a constant upward velocity followed by a constant downwani velo​
Physics
1 answer:
yulyashka [42]3 years ago
6 0

Answer:

Option (b) is correct.

Explanation:

The motion under the influence of gravity is called projectile motion.

The acceleration due to gravity is constant through out the motion and it is always acting downwards.

When an athlete jumps and follow the projectile path, it always have the same horizontal velocity as there is no acceleration in the horizontal direction.

Also he has the vertical acceleration constant which is equal to the acceleration due to gravity and acts towards the center of earth.  

Option (b) is correct.

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You're driving down the highway late one night at 20 m/s when a deer steps onto the road 49 m in front of you. You reaction time
Leno4ka [110]

Answer:

v = 26.7 m/s

Explanation:

Given,

speed of the car = 20 m/s

distance between the car and the deer = 49 m

time taken to press the brake = 0.50 s

maximum deceleration of the car = 10 m/s²

Now,

distance travel by the car in 0.5 s = u x t = 20 x 0.5 = 10 m

distance travel by the car after the break is pressed

Using equation of motion

v² = u² + 2 a s

0² = 20² - 2 x 10 x s

s = 20 m

Total distance travel by the car = 20 + 10 = 30 m

Distance between deer and car = 49-30 = 19 m.

b. Maximum speed a car could have

Distance travel by the car in reaction time = v' x 0.5

v' is the maximum speed of the car.

maximum distance car can cover = 49 - 0.5 v'

Now, Using equation of motion

v² = u² + 2 a s

0² =v'² - 2 x 10 x (49- 0.5 x v')

v'² +10 v' -980 = 0

By solving

v = 26.7 m/s

Hence, maximum speed of the car can be 26.7 m/s

 

4 0
3 years ago
How much heat is contained in 100 kg of water at 60.0 °C?
attashe74 [19]
First we need to write down heat capacity for water which is constant.
cp=4186 J/(kg*K)

The equation for Energy that we will be calculating is:

E=cp*m*T
where m is mass and T is absolute temperature (273,15 + 60 in this case). Replacing all the values in equation we get:

E = 4186*100*333,15 = 139 456 590 J
6 0
3 years ago
15.Restore the battery setting to 10 V. Now change the number of loops from 4 to 3. Explain what happens to the magnitude and di
lozanna [386]

Answer:

we see it is a linear relationship.

Explanation:

The magnetic flux is u solenoid is

      B = μ₀ N/L   I

where N is the number of loops, L the length and I the current

By applying this expression to our case we have that the current is the same in all cases and we can assume the constant length. Consequently we see that the magnitude of the magnetic field decreases with the number of loops

      B = (μ₀ I / L)  N

the amount between paracentesis constant, in the case of 4 loop the field is worth

      B = cte 4

N       B

4       4 cte

3       3 cte

2       2 cte

1        1 cte

as we see it is a linear relationship.

In addition, this effect for such a small number of turns the direction of the field that is parallel to the normal of the lines will oscillate,

6 0
3 years ago
Help me with this question please
vichka [17]

Answer:

Its true i'm pretty sure

Explanation:

7 0
3 years ago
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What is role of skin in balancing body temperature during strenous excervise
trapecia [35]

Answer:

The skin releases sweat

Explanation:

The body temperature is necessary to maintain homeostasis. Skin  controls body temperature by sweating when it is too heated.

3 0
3 years ago
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