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3 years ago

Mary has a mass of 40 kg and sprints at 1 m/s. How much kinetic energy does she have?

Physics

1 answer:

Sav [38]3 years ago

8 0

Answer:

20 J

Explanation:

Kinetic energy is given as half of the product of mass and the square of velocity of an object:

KE = $\frac{1}{2}mv^2$

where m = mass = 40 kg

v = velocity = 1 m/s

Hence, Mary's kinetic energy is:

KE = $\frac{1}{2} * 40 * 1^2$

KE = 20 * 1 = 20 J

She has a kinetic energy of 20 J.

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Drivers should train themselves to scan ahead two seconds looking for ________ hazards and from 10-12 seconds down the road for

xxTIMURxx [149]

Answer:

Immediate, potential

Explanation:

In america there are many safety council .in which drivers are trained. According to american safety council in america the drivers are trained in such a way that they can ahead two seconds so that there will not be any immediate hazards and 10 to 12 seconds down the road for potential hazards

So in the blanks there will be immediate and potential

3 0

2 years ago

A. State whether the acceleration is positive, negative or zero for each section in the speed versus

bazaltina [42]

Answer:

a=positive

b=0

c=positive

d=negative

Explanation:

a=acceleration depends on the speed and time. if the speed and time are increasing at the same rate, the acceleration value will be positive as the vehicle is speeding up.

b=the speed and time are not increasing, therefore the vehicle is either stationary or travelling at a steady pace.

c=same explanation as a

d=the speed and time are not increasing at the same rate as the speed is decreasing. this means that the car is slowing down

5 0

2 years ago

How does the magnitude of the electrical force between a pair of charged particles change when they are brought to half their or

Ostrovityanka [42]

Answer:

5. Quadruple

Explanation:

The electrostatic force between two charged particles is given by:

$F=k\frac{q_1 q_2}{r^2}$

where

k is the Coulomb's constant

q1, q2 are the two charges

r is the separation between the charges

If the distance between the charges is reduced to half,

$r' = \frac{r}{2}$

So the new force will be

$F'=k\frac{q_1 q_2}{(r/2)^2}=4(k\frac{q_1 q_2}{r^2})=4F$

So, the force will quadruple.

4 0

3 years ago

A charge of q= +15 uC moves in a Northeast direction with a speed 5 m/s, 25 degrees East of a magnetic field, pointing North, wi

grin007 [14]

Explanation:

It is given that,

Magnitude of charge, $q=15\ \mu C=15\times 10^{-6}\ C$

It moves in northeast direction with a speed of 5 m/s, 25 degrees East of a magnetic field.

Magnetic field, $B=0.08\ j$

Velocity, $v=(5\ cos25)i+(5\ sin25)j$

$v=[(4.53)i+(2.11)j]\ m/s$

We need to find the magnitude of force on the charge. Magnetic force is given by :

$F=q(v\times B)$

$F=15\times 10^{-6}[(4.53i+2.11j)\times 0.08\ j]$

<em>Since</em>, $i\times j=k\ and\ j\times j=0$

$F=15\times 10^{-6}[(4.53i)\times (0.08)\ j]$

$F=0.00000543\ kN$

$F=5.43\times 10^{-6}\ kN$

So, the force acting on the charge is $5.43\times 10^{-6}\ kN$ and is moving in positive z axis. Hence, this is the required solution.

6 0

3 years ago

Which of the following represents a chemical change to matter? A. digestion of food B. melting an ice cube C. shredding paper D.

guajiro [1.7K]

The answer is A. digestion of food. The chemical change to matter means that the molecule structure has been destroyed. For B, C and D. the matter are still ice, paper and ice. So they are physical change.

8 0

2 years ago