Physics: When do we have positive/negative and zero acceleration.Write down the termspls help mee

When do we have positive/negative and zero acceleration.Write

aquinomelodyr

26.07.2021

We have negative acceleration when an object projected upwards, while positive acceleration is a free fall.

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Izayoi

26.07.2021

Positive acceleration is when an object is increasing its velocity, speeding up.

Negative acceleration is when an object is decreasing its velocity, slowing down from it’s motion.

Zero acceleration is when an object is either at rest or moving without speeding up or slowing down, in a constant way.

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yalley1982

18.07.2020

$4.2\times10^3 W$

$2.67\times 10^4 W$

Explanation:

Given:

Mass of the rider plus the bike, $m=2\times10^2 kg$

Speed of the motorbike, u= 20 m/s

Force of resistance, $F=2.1\times10^2N$

Power necessary to sustain speed can be calculated as follows:

1. When road is level

Power = force x velocity

P= F x u

$P=(2.1\times10^2N)(20 m/s) = 4.2\times10^3 W$

2. When the road is sloped at an angle 35°

An additional force will act due to component of gravity that is

$= mg sin \theta$

So,

$P = (F+mgsin\theta)u\\ P= (2.1\times10^2+2\times10^2\times 9.8 \times sin35^o)(20)=2.67\times 10^4 W$

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