Answer:
17.64 km/h
Explanation:
mass of car, m = 1000 kg
Kinetic energy of car, K = 1.2 x 10^4 J
Let the speed of car is v.
Use the formula for kinetic energy.
By substituting the values
v = 4.9 m/s
Now convert metre per second into km / h
We know that
1 km = 1000 m
1 h = 3600 second
So, 
v = 17.64 km/h
Thus, the reading of speedometer is 17.64 km/h.
Answer:
1 km
Explanation:
= Gap between antennas = 600 m
= Frequency = 1 MHz
= Distance to receiver = 2 km
c = Speed of light = 
Wavelength is given by
Distance to be moved is given by
The distance to be moved is 1 km north.
Answer:
Density of jacket will be 
Explanation:
We know that weight of water displaced= buoyant force=weight of man
Now volume of water displaced 
Density of water 
So weight of water displaced 
So weight of jacket = 98-75 = 23 kg
We have given volume of the jacket = 
So density of jacket 
Answer:
F = 1.2×10⁻³ N
Explanation:
From the question,
Applying newton's second law of motion,
F = m(v-u)/t................... Equation 1
Given: F = magnitude of the average force exerted on the ball, m = mass of the ball, v = final velocity, u = initial velocity, t = time of contact.
Note: let downward be negative and upward be positive.
Given: m = 48 g = 48/1000 = 0.048 kg, v = 17 m/s, u = -28 m/s (downward),
t = 1800 s
Substitute into equation 1
F = 0.048(17-[28])/1800
F = 1.2×10⁻³ N
The answer - all of the above.
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