Q: A dancer demonstrating dance steps along a straight line. The position time graph is given. Find the average velocity for the dance step depicted by AB.

For the dance step depicted by AB :Path length \$=\$ 0;Displacement \$=\$ 0Time taken, t \$=\$ 1 sAverage velocity \$= \displaystyle \dfrac{displacement}{time \ taken}\$\$ \displaystyle = \dfrac{0}{1} =0\$

Q: A person travels a distance of \$72 \ km\$ in \$4\$ hours. Calculate speed in \$m/s\$.

Distance, \$S=72\ km\$Time, \$t=4 \ hr\$Speed \$=\dfrac{72}{4}km/hr\\ = \dfrac{72}{4}\times \dfrac{5}{18}\\=5 \ m/s\$

Q: Speed of a body depends on

Speed is defined as \$Speed = \dfrac{\text{Distance travelled}}{\text{Time interval}}\$Hence speed depends both on time and distance travelled by the body.So both A and C are correct.

Q: Name one unit of time bigger than a second.

\$1\ kilosecond=1000\ seconds\$

Question 1

A dancer demonstrating dance steps along a straight line. The displacement time graph is given.Find the average speed for the dance step depicted by CD.

Accepted Answer

Average speed is defined as the ratio of the distance covered to the total time taken .Average speed $s_{av} = \dfrac{ Distance \ covered}{ time \ taken}$For step CD Initial position is $4$, final position is $0$, hence distance covered $=4 \ m$Total time is $6-4 = 2 \ sec$So average speed is $s = \dfrac{4}{2}=2\ m/s$So option $B$ is correct.

Question 2

A dancer demonstrating dance steps along a straight line. The position time graph is given. Find the average velocity for the dance step depicted by AB.

Accepted Answer

For the dance step depicted by AB :Path length $=$ 0;Displacement $=$ 0Time taken, t $=$ 1 sAverage velocity $= \displaystyle \dfrac{displacement}{time \ taken}$$ \displaystyle = \dfrac{0}{1} =0$

Question 3

A person travels a distance of $72 \ km$ in $4$ hours. Calculate speed in $m/s$.

Accepted Answer

Distance, $S=72\ km$Time, $t=4 \ hr$Speed $=\dfrac{72}{4}km/hr\ = \dfrac{72}{4}\times \dfrac{5}{18}\=5 \ m/s$

Question 4

Speed of a body depends on

Accepted Answer

Speed is defined as $Speed = \dfrac{\text{Distance travelled}}{\text{Time interval}}$Hence speed depends both on time and distance travelled by the body.So both A and C are correct.

Question 5

100 years make 10 decades.

Accepted Answer

Every century is divided into 10 decades.

Question 6

A body at rest cannot have ______ and ______.

Accepted Answer

A body at rest can not have speed and velocity because distance and displacement do not change with time.Answer: velocity and speed

Question 7

Name one unit of time bigger than a second.

Accepted Answer

$1\ kilosecond=1000\ seconds$

Question 8

Rain is falling vertically with a speed of 1.7 m/s. A girl is walking with speed of 1.0 m/s in the N - E (north-east) direction. To shield herself she holds her umbrella making an approximate angle $θ$ with the vertical in a certain direction. Then

Accepted Answer

Toppr Ask Answer

Question 9

What is a leap year ?

Accepted Answer

A leap year is a year containing an extra day. It has 366 days instead of the normal 365 days. The extra day is added in February, which has 29 days instead of the normal 28 days. Leap years occur every 4 years.

Question 10

A dancer demonstrating dance steps along a straight line. The position-time graph is given below.Find the average velocity of the dancer during the time interval between t $=$ 4.5 s to t $=$ 9 s

Accepted Answer

Displacement = final position - initial positionFrom graph final position is zero at $9\ s$.From graph initial position is $4\ m$ at $4.5\ s$.Here, displacement $=-4\ m$Time taken, $t=9-4.5$$\Rightarrow t = 4.5\ s$Average velocity$(V_{avg})$$V_{avg} \displaystyle = \dfrac{displacement}{time}$$\Rightarrow V_{avg}= \displaystyle \dfrac{-4}{4.5} $$ \Rightarrow V_{avg} = -0.89  m  s^{-1}$

Motion And Time

Physics
3938 Views

A dancer demonstrating dance steps along a straight line. The displacement time graph is given.

Find the average speed for the dance step depicted by CD.

A dancer demonstrating dance steps along a straight line. The position time graph is given. Find the average velocity for the dance step depicted by AB.

A person travels a distance of $72 k m$ in $4$ hours. Calculate speed in $m / s$ .

Speed of a body depends on

100 years make 10 decades.

Every century is divided into 10 decades.

A body at rest cannot have and .

Name one unit of time bigger than a second.

Rain is falling vertically with a speed of 1.7 m/s. A girl is walking with speed of 1.0 m/s in the N - E (north-east) direction. To shield herself she holds her umbrella making an approximate angle $θ$ with the vertical in a certain direction. Then

What is a leap year ?

A dancer demonstrating dance steps along a straight line. The position-time graph is given below.

Find the average velocity of the dancer during the time interval between t $=$ 4.5 s to t $=$ 9 s

Motion And Time

Physics 3938 Views

A dancer demonstrating dance steps along a straight line. The displacement time graph is given. Find the average speed for the dance step depicted by CD.

A dancer demonstrating dance steps along a straight line. The position time graph is given. Find the average velocity for the dance step depicted by AB.

A person travels a distance of 72 km in 4 hours. Calculate speed in m/s.

Speed of a body depends on

100 years make 10 decades.

Every century is divided into 10 decades.

A body at rest cannot have ______ and ______.

Name one unit of time bigger than a second.

Rain is falling vertically with a speed of 1.7 m/s. A girl is walking with speed of 1.0 m/s in the N - E (north-east) direction. To shield herself she holds her umbrella making an approximate angle θ with the vertical in a certain direction. Then

What is a leap year ?

A dancer demonstrating dance steps along a straight line. The position-time graph is given below. Find the average velocity of the dancer during the time interval between t = 4.5 s to t = 9 s

Physics
3938 Views

A dancer demonstrating dance steps along a straight line. The displacement time graph is given.

Find the average speed for the dance step depicted by CD.

A person travels a distance of $72 k m$ in $4$ hours. Calculate speed in $m / s$ .

A body at rest cannot have and .

Rain is falling vertically with a speed of 1.7 m/s. A girl is walking with speed of 1.0 m/s in the N - E (north-east) direction. To shield herself she holds her umbrella making an approximate angle $θ$ with the vertical in a certain direction. Then

A dancer demonstrating dance steps along a straight line. The position-time graph is given below.

Find the average velocity of the dancer during the time interval between t $=$ 4.5 s to t $=$ 9 s