Mechanics | Relativity Answers

A person is riding in a car which is moving at a constant speed around a circular arc.

The person has an accelerometer on their mobile phone and uses it to measure a lateral (horizontal) acceleration of 5.6 m s−2.

If the car was traveling at 50 km h−1 (14 m s−1) then what was the radius of the curve that car was traveling along? (to 2 s.f)

A 64.0 kg person is riding an elevator as shown in the figure above. The elevator is accelerating upwards at a rate of 0.682 m s−2.

For this problem use g = 9.81 m s−2

What is the magnitude of the normal force, the force on the person from the elevator? (in N to 3.s.f)

A car is moving around a banked curve of radius 86 m at a constant speed. The road is banked at an angle of 11° and the car is moving at just the correct speed to ensure that there are no lateral frictional forces on the tyres - that is the only forces acting on the car are the force of gravity and the normal force from the road.

At what speed is the car moving? (in m s−1 to 2 s.f)

A person swings a 350 g ball around their head on a string as shown in the figure above.

The tension in the string is 10 N and the ball moves in a circle of radius 0.93 m at a constant speed of 5.0 m s−1.

What is the angle θ that the string makes with the horizontal? (in ° to 2 s.f)

A reckless hunter is on a boat which is stationary in the middle of a lake.

They fire their gun horizontally 10 times. Each time they fire, a 12 g bullet leaves the gun at a speed of 410 m s−1.

What is the speed of the boat after they have have finished firing their gun if the total mass of the boat, hunter, and gun is 150 kg? (in m s−1 to 2 s.f)

Assume no drag forces from the water.

A spring with a spring constant of 6.2 N m−1 is used to launch a 5.0 g slider along a frictionless track as shown in the figure above. The spring is compressed by 16 cm.

To what height h above the height labeled 0 m in the figure does the slider reach? (in m to 2 s.f)

Three resistors R1=2.0Ω, R2=12.0Ω, and R3=8.0Ω are connected in series with a 9.0-V battery. (a) Show the illustration (b) Calculate the current in the circuit and show that the sum of all voltage changes around the circuit is zero.

If the two stage rocket of a weights 100 kg and 10 kg separately and contains 800 kg and 90 kg fuel

separately, what is the final velocity that can be achieved with an exhaust velocity of 1.5 km/sec. (Given

log10 =2.3 and log102 =0.3 )

Find the moment of inertia of a circular disc (i) about an axis through its center and perpendicular

to its plane (ii) about a diameter.

Arthur and Betty start walking toward each other when they are 100 m apart. Arthur has a speed of 3.0 (2.0m / m / s and Betty has a speed of How long does it take for them to meet?