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lukranit [14]
3 years ago
13

A car is traveling at 20 meters/second and is brought to rest by applying brakes over a period of 4 seconds. What is its average

acceleration over this time interval?
Physics
2 answers:
frez [133]3 years ago
8 0
 (u) = 20 m/s 
(v) = 0 m/s 
<span> (t) = 4 s 
</span>
<span>0 = 20 + a(4) 

</span><span>4 x a = -20 
</span>
so, the answer is <span>-5 m/s^2. or -5 meter per second</span>
Feliz [49]3 years ago
8 0
The answer is -5 m/s^2. or -5 meter per second
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a ship A , steaming in a direction 030° with a steady 12 km/h, sight a ship B. The velocity of B relative to A is 10km/h in a di
pickupchik [31]

Answer: 11 km/h at 339° compass

Explanation:

A sees B moving south at 0 km/h

A is moving north at 12cos30 = 10.392 km/h

Therefore B must be moving north at 10.392 k/h

A is moving east at 12sin30 = 6 km/h

B appears to be moving west at 10 km/h

Therefore B must be moving west at 10 - 6 = 4 km/h

B is moving v = √(4² + 10.392²) = 11.135... 11 km/h

θ = arctan( -4 / 10.392) = -21.05 = 339°

8 0
3 years ago
A frictionless pendulum is made with a bob of mass 19.7 kg. The bob is held at height = 0.934 meter above the bottom of its traj
Alika [10]

Answer:

265 J

Explanation:

Energy=PE+KE=mgh+ 0.5mv^{2} where KE is kinetic energy, PE is potential energy, m is the mass of an object, v is the speed, h is the height and g is acceleration due to gravity.

Substituting 19.7 Kg for mass, 0.934 for h, 2.93 for v and 9.81 for g then

Energy=19.7(9.81*0.934+0.5*2.93^{2})=265.063303\approx 265 J

4 0
3 years ago
Find the electric field at a point midway between two charges of 30.0×10 power -9 and 60.0×10 power -9 separated by a distance o
KATRIN_1 [288]

Answer:

The electric field at a point midway between the two charges, E = -1.8 * 10⁴ N/C

Explanation:

Let the midpoint of the two charges be considered as the origin, and charge A = 30.0 * 10⁻⁹ C be moving in the +x- axis and the charge B = 60.0 * 10⁻⁹ C be moving in the -x-axis.

Electric field, E = kQ/r² where k is a constant = 9.0 * 10⁹  N.m²/C², Q = quantity of charge, r = distance of separation

In the given question,r = 30.0 cm = 0.03 m; the midway point between A and B = 0.03/2 = 0.015 m

Electric field due to charge A

Ea = +(9.0 * 10⁹  N.m²/C² * 30.0 * 10⁻⁹ ) / ( 0.015 m)²

Ea =  +1.8 * 10⁴ N/C

Electric field due to charge B

Eb = -(9.0 * 10⁹  N.m²/C² * 60.0 * 10⁻⁹ ) / ( 0.015 m)²

Eb =  -3.6 * 10⁴ N/C

The resultant electric field E = Ea + Eb

E = (+1.8 * 10⁴  +  -3.6 * 10⁴) N/C

E = -1.8 * 10⁴ N/C

Therefore, the electric field at a point midway between the two charges, E = -1.8 * 10⁴ N/C

7 0
3 years ago
How is a magnetable to pick up bits of metal without actually touching them?
lisov135 [29]

C.There is an invisible magnetic field around the magnet where it exerts magnetic force

7 0
3 years ago
What is the force on a 1,000 kilogram-elevator that is falling freely under the acceleration of gravity only?
likoan [24]

           Force = (mass) · (acceleration)

                     = (1,000 kg) · (9.8 m/s²)

                     =      9,800 newtons

Why are you still having a problem with      F = M · a  ?
8 0
3 years ago
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